Implement CTABLES procedure.
[pspp] / src / language / stats / ctables.c
diff --git a/src/language/stats/ctables.c b/src/language/stats/ctables.c
new file mode 100644 (file)
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+/* PSPP - a program for statistical analysis.
+   Copyright (C) 2021 Free Software Foundation, Inc.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>. */
+
+#include <config.h>
+
+#include <math.h>
+#include <errno.h>
+
+#include "data/casegrouper.h"
+#include "data/casereader.h"
+#include "data/casewriter.h"
+#include "data/data-in.h"
+#include "data/data-out.h"
+#include "data/dataset.h"
+#include "data/dictionary.h"
+#include "data/mrset.h"
+#include "data/subcase.h"
+#include "data/value-labels.h"
+#include "language/command.h"
+#include "language/dictionary/split-file.h"
+#include "language/lexer/format-parser.h"
+#include "language/lexer/lexer.h"
+#include "language/lexer/token.h"
+#include "language/lexer/variable-parser.h"
+#include "libpspp/array.h"
+#include "libpspp/assertion.h"
+#include "libpspp/hash-functions.h"
+#include "libpspp/hmap.h"
+#include "libpspp/i18n.h"
+#include "libpspp/message.h"
+#include "libpspp/string-array.h"
+#include "math/mode.h"
+#include "math/moments.h"
+#include "math/percentiles.h"
+#include "math/sort.h"
+#include "output/pivot-table.h"
+
+#include "gl/minmax.h"
+#include "gl/xalloc.h"
+
+#include "gettext.h"
+#define _(msgid) gettext (msgid)
+#define N_(msgid) (msgid)
+
+struct ctables;
+
+/* The three forms of weighting supported by CTABLES. */
+enum ctables_weighting
+  {
+    CTW_EFFECTIVE,             /* Effective base weight (WEIGHT subcommand). */
+    CTW_DICTIONARY,            /* Dictionary weight. */
+    CTW_UNWEIGHTED             /* No weight. */
+#define N_CTWS 3
+  };
+\f
+/* CTABLES table areas. */
+
+enum ctables_area_type
+  {
+    /* Within a section, where stacked variables divide one section from
+       another.
+
+       Keep CTAT_LAYER after CTAT_LAYERROW and CTAT_LAYERCOL so that
+       parse_ctables_summary_function() parses correctly. */
+    CTAT_TABLE,                  /* All layers of a whole section. */
+    CTAT_LAYERROW,               /* Row in one layer within a section. */
+    CTAT_LAYERCOL,               /* Column in one layer within a section. */
+    CTAT_LAYER,                  /* One layer within a section. */
+
+    /* Within a subtable, where a subtable pairs an innermost row variable with
+       an innermost column variable within a single layer.  */
+    CTAT_SUBTABLE,               /* Whole subtable. */
+    CTAT_ROW,                    /* Row within a subtable. */
+    CTAT_COL,                    /* Column within a subtable. */
+#define N_CTATS 7
+  };
+
+static const char *ctables_area_type_name[N_CTATS] = {
+  [CTAT_TABLE] = "TABLE",
+  [CTAT_LAYER] = "LAYER",
+  [CTAT_LAYERROW] = "LAYERROW",
+  [CTAT_LAYERCOL] = "LAYERCOL",
+  [CTAT_SUBTABLE] = "SUBTABLE",
+  [CTAT_ROW] = "ROW",
+  [CTAT_COL] = "COL",
+};
+
+/* Summary statistics for an area. */
+struct ctables_area
+  {
+    struct hmap_node node;
+    const struct ctables_cell *example;
+
+    /* Sequence number used for CTSF_ID. */
+    size_t sequence;
+
+    /* Weights for CTSF_areaPCT_COUNT, CTSF_areaPCT_VALIDN, and
+       CTSF_areaPCT_TOTALN. */
+    double count[N_CTWS];
+    double valid[N_CTWS];
+    double total[N_CTWS];
+
+    /* Sums for CTSF_areaPCT_SUM. */
+    struct ctables_sum *sums;
+  };
+
+struct ctables_sum
+  {
+    double sum[N_CTWS];
+  };
+\f
+/* CTABLES summary functions. */
+
+enum ctables_function_type
+  {
+    /* A function that operates on data in a single cell.  It operates on
+       effective weights.  It does not have an unweighted version. */
+    CTFT_CELL,
+
+    /* A function that operates on data in a single cell.  The function
+       operates on effective weights and has a U-prefixed unweighted
+       version. */
+    CTFT_UCELL,
+
+    /* A function that operates on data in a single cell.  It operates on
+       dictionary weights, and has U-prefixed unweighted version and an
+       E-prefixed effective weight version. */
+    CTFT_UECELL,
+
+    /* A function that operates on an area of cells.  It operates on effective
+       weights and has a U-prefixed unweighted version. */
+    CTFT_AREA,
+  };
+
+enum ctables_format
+  {
+    CTF_COUNT,                  /* F40.0. */
+    CTF_PERCENT,                /* PCT40.1. */
+    CTF_GENERAL                 /* Variable's print format. */
+  };
+
+enum ctables_function_availability
+  {
+    CTFA_ALL,                /* Any variables. */
+    CTFA_SCALE,              /* Only scale variables, totals, and subtotals. */
+    //CTFA_MRSETS,             /* Only multiple-response sets */
+  };
+
+enum ctables_summary_function
+  {
+#define S(ENUM, NAME, TYPE, FORMAT, AVAILABILITY) ENUM,
+#include "ctables.inc"
+#undef S
+  };
+
+enum {
+#define S(ENUM, NAME, TYPE, FORMAT, AVAILABILITY) +1
+  N_CTSF_FUNCTIONS =
+#include "ctables.inc"
+#undef S
+};
+
+struct ctables_function_info
+  {
+    struct substring basename;
+    enum ctables_function_type type;
+    enum ctables_format format;
+    enum ctables_function_availability availability;
+
+    bool u_prefix;              /* Accepts a 'U' prefix (for unweighted)? */
+    bool e_prefix;              /* Accepts an 'E' prefix (for effective)? */
+    bool is_area;               /* Needs an area prefix. */
+  };
+static const struct ctables_function_info ctables_function_info[N_CTSF_FUNCTIONS] = {
+#define S(ENUM, NAME, TYPE, FORMAT, AVAILABILITY)                       \
+  [ENUM] = {                                                            \
+    .basename = SS_LITERAL_INITIALIZER (NAME),                          \
+    .type = TYPE,                                                       \
+    .format = FORMAT,                                                   \
+    .availability = AVAILABILITY,                                       \
+    .u_prefix = (TYPE) == CTFT_UCELL || (TYPE) == CTFT_UECELL || (TYPE) == CTFT_AREA, \
+    .e_prefix = (TYPE) == CTFT_UECELL,                                  \
+    .is_area = (TYPE) == CTFT_AREA                                      \
+  },
+#include "ctables.inc"
+#undef S
+};
+
+static struct fmt_spec
+ctables_summary_default_format (enum ctables_summary_function function,
+                                const struct variable *var)
+{
+  static const enum ctables_format default_formats[] = {
+#define S(ENUM, NAME, TYPE, FORMAT, AVAILABILITY) [ENUM] = FORMAT,
+#include "ctables.inc"
+#undef S
+  };
+  switch (default_formats[function])
+    {
+    case CTF_COUNT:
+      return (struct fmt_spec) { .type = FMT_F, .w = 40 };
+
+    case CTF_PERCENT:
+      return (struct fmt_spec) { .type = FMT_PCT, .w = 40, .d = 1 };
+
+    case CTF_GENERAL:
+      return *var_get_print_format (var);
+
+    default:
+      NOT_REACHED ();
+    }
+}
+
+static enum ctables_function_availability
+ctables_function_availability (enum ctables_summary_function f)
+{
+  static enum ctables_function_availability availability[] = {
+#define S(ENUM, NAME, TYPE, FORMAT, AVAILABILITY) [ENUM] = AVAILABILITY,
+#include "ctables.inc"
+#undef S
+  };
+
+  return availability[f];
+}
+
+static bool
+parse_ctables_summary_function (struct lexer *lexer,
+                                enum ctables_summary_function *function,
+                                enum ctables_weighting *weighting,
+                                enum ctables_area_type *area)
+{
+  if (!lex_force_id (lexer))
+    return false;
+
+  struct substring name = lex_tokss (lexer);
+  if (ss_ends_with_case (name, ss_cstr (".LCL"))
+      || ss_ends_with_case (name, ss_cstr (".UCL"))
+      || ss_ends_with_case (name, ss_cstr (".SE")))
+    {
+      lex_error (lexer, _("Support for LCL, UCL, and SE summary functions "
+                          "is not yet implemented."));
+      return false;
+    }
+
+  bool u = ss_match_byte (&name, 'U') || ss_match_byte (&name, 'u');
+  bool e = !u && (ss_match_byte (&name, 'E') || ss_match_byte (&name, 'e'));
+
+  bool has_area = false;
+  *area = 0;
+  for (enum ctables_area_type at = 0; at < N_CTATS; at++)
+    if (ss_match_string_case (&name, ss_cstr (ctables_area_type_name[at])))
+      {
+        has_area = true;
+        *area = at;
+
+        if (ss_equals_case (name, ss_cstr ("PCT")))
+          {
+            /* Special case where .COUNT suffix is omitted. */
+            *function = CTSF_areaPCT_COUNT;
+            *weighting = CTW_EFFECTIVE;
+            lex_get (lexer);
+            return true;
+          }
+        break;
+      }
+
+  for (int f = 0; f < N_CTSF_FUNCTIONS; f++)
+    {
+      const struct ctables_function_info *cfi = &ctables_function_info[f];
+      if (ss_equals_case (cfi->basename, name))
+        {
+          *function = f;
+          if ((u && !cfi->u_prefix) || (e && !cfi->e_prefix) || (has_area != cfi->is_area))
+            break;
+
+          *weighting = (e ? CTW_EFFECTIVE
+                        : u ? CTW_UNWEIGHTED
+                        : cfi->e_prefix ? CTW_DICTIONARY
+                        : CTW_EFFECTIVE);
+          lex_get (lexer);
+          return true;
+        }
+    }
+
+  lex_error (lexer, _("Expecting summary function name."));
+  return false;
+}
+
+static const char *
+ctables_summary_function_name (enum ctables_summary_function function,
+                               enum ctables_weighting weighting,
+                               enum ctables_area_type area,
+                               char *buffer, size_t bufsize)
+{
+  const struct ctables_function_info *cfi = &ctables_function_info[function];
+  snprintf (buffer, bufsize, "%s%s%s",
+            (weighting == CTW_UNWEIGHTED ? "U"
+             : weighting == CTW_DICTIONARY ? ""
+             : cfi->e_prefix ? "E"
+             : ""),
+            cfi->is_area ? ctables_area_type_name[area] : "",
+            cfi->basename.string);
+  return buffer;
+}
+
+static const char *
+ctables_summary_function_label__ (enum ctables_summary_function function,
+                                  enum ctables_weighting weighting,
+                                  enum ctables_area_type area)
+{
+  bool w = weighting != CTW_UNWEIGHTED;
+  bool d = weighting == CTW_DICTIONARY;
+  enum ctables_area_type a = area;
+  switch (function)
+    {
+    case CTSF_COUNT:
+      return d ? N_("Count") : w ? N_("Adjusted Count") : N_("Unweighted Count");
+
+    case CTSF_areaPCT_COUNT:
+      switch (a)
+        {
+        case CTAT_TABLE: return w ? N_("Table %") : N_("Unweighted Table %");
+        case CTAT_LAYER: return w ? N_("Layer %") : N_("Unweighted Layer %");
+        case CTAT_LAYERROW: return w ? N_("Layer Row %") : N_("Unweighted Layer Row %");
+        case CTAT_LAYERCOL: return w ? N_("Layer Column %") : N_("Unweighted Layer Column %");
+        case CTAT_SUBTABLE: return w ? N_("Subtable %") : N_("Unweighted Subtable %");
+        case CTAT_ROW: return w ? N_("Row %") : N_("Unweighted Row %");
+        case CTAT_COL: return w ? N_("Column %") : N_("Unweighted Column %");
+        }
+      NOT_REACHED ();
+
+    case CTSF_areaPCT_VALIDN:
+      switch (a)
+        {
+        case CTAT_TABLE: return w ? N_("Table Valid N %") : N_("Unweighted Table Valid N %");
+        case CTAT_LAYER: return w ? N_("Layer Valid N %") : N_("Unweighted Layer Valid N %");
+        case CTAT_LAYERROW: return w ? N_("Layer Row Valid N %") : N_("Unweighted Layer Row Valid N %");
+        case CTAT_LAYERCOL: return w ? N_("Layer Column Valid N %") : N_("Unweighted Layer Column Valid N %");
+        case CTAT_SUBTABLE: return w ? N_("Subtable Valid N %") : N_("Unweighted Subtable Valid N %");
+        case CTAT_ROW: return w ? N_("Row Valid N %") : N_("Unweighted Row Valid N %");
+        case CTAT_COL: return w ? N_("Column Valid N %") : N_("Unweighted Column Valid N %");
+        }
+      NOT_REACHED ();
+
+    case CTSF_areaPCT_TOTALN:
+      switch (a)
+        {
+        case CTAT_TABLE: return w ? N_("Table Total N %") : N_("Unweighted Table Total N %");
+        case CTAT_LAYER: return w ? N_("Layer Total N %") : N_("Unweighted Layer Total N %");
+        case CTAT_LAYERROW: return w ? N_("Layer Row Total N %") : N_("Unweighted Layer Row Total N %");
+        case CTAT_LAYERCOL: return w ? N_("Layer Column Total N %") : N_("Unweighted Layer Column Total N %");
+        case CTAT_SUBTABLE: return w ? N_("Subtable Total N %") : N_("Unweighted Subtable Total N %");
+        case CTAT_ROW: return w ? N_("Row Total N %") : N_("Unweighted Row Total N %");
+        case CTAT_COL: return w ? N_("Column Total N %") : N_("Unweighted Column Total N %");
+        }
+      NOT_REACHED ();
+
+    case CTSF_MAXIMUM: return N_("Maximum");
+    case CTSF_MEAN: return w ? N_("Mean") : N_("Unweighted Mean");
+    case CTSF_MEDIAN: return w ? N_("Median") : N_("Unweighted Median");
+    case CTSF_MINIMUM: return N_("Minimum");
+    case CTSF_MISSING: return w ? N_("Missing") : N_("Unweighted Missing");
+    case CTSF_MODE: return w ? N_("Mode") : N_("Unweighted Mode");
+    case CTSF_PTILE: NOT_REACHED ();
+    case CTSF_RANGE: return N_("Range");
+    case CTSF_SEMEAN: return w ? N_("Std Error of Mean") : N_("Unweighted Std Error of Mean");
+    case CTSF_STDDEV: return w ? N_("Std Deviation") : N_("Unweighted Std Deviation");
+    case CTSF_SUM: return w ? N_("Sum") : N_("Unweighted Sum");
+    case CTSF_TOTALN: return (d ? N_("Total N")
+                              : w ? N_("Adjusted Total N")
+                              : N_("Unweighted Total N"));
+    case CTSF_VALIDN: return (d ? N_("Valid N")
+                              : w ? N_("Adjusted Valid N")
+                              : N_("Unweighted Valid N"));
+    case CTSF_VARIANCE: return w ? N_("Variance") : N_("Unweighted Variance");
+    case CTSF_areaPCT_SUM:
+      switch (a)
+        {
+        case CTAT_TABLE: return w ? N_("Table Sum %") : N_("Unweighted Table Sum %");
+        case CTAT_LAYER: return w ? N_("Layer Sum %") : N_("Unweighted Layer Sum %");
+        case CTAT_LAYERROW: return w ? N_("Layer Row Sum %") : N_("Unweighted Layer Row Sum %");
+        case CTAT_LAYERCOL: return w ? N_("Layer Column Sum %") : N_("Unweighted Layer Column Sum %");
+        case CTAT_SUBTABLE: return w ? N_("Subtable Sum %") : N_("Unweighted Subtable Sum %");
+        case CTAT_ROW: return w ? N_("Row Sum %") : N_("Unweighted Row Sum %");
+        case CTAT_COL: return w ? N_("Column Sum %") : N_("Unweighted Column Sum %");
+        }
+      NOT_REACHED ();
+
+    case CTSF_areaID:
+      switch (a)
+        {
+        /* Don't bother translating these: they are for developers only. */
+        case CTAT_TABLE: return "Table ID";
+        case CTAT_LAYER: return "Layer ID";
+        case CTAT_LAYERROW: return "Layer Row ID";
+        case CTAT_LAYERCOL: return "Layer Column ID";
+        case CTAT_SUBTABLE: return "Subtable ID";
+        case CTAT_ROW: return "Row ID";
+        case CTAT_COL: return "Column ID";
+        }
+      NOT_REACHED ();
+    }
+
+  NOT_REACHED ();
+}
+
+static struct pivot_value *
+ctables_summary_function_label (enum ctables_summary_function function,
+                                enum ctables_weighting weighting,
+                                enum ctables_area_type area,
+                                double percentile)
+{
+  if (function == CTSF_PTILE)
+    {
+      char *s = (weighting != CTW_UNWEIGHTED
+                 ? xasprintf (_("Percentile %.2f"), percentile)
+                 : xasprintf (_("Unweighted Percentile %.2f"), percentile));
+      return pivot_value_new_user_text_nocopy (s);
+    }
+  else
+    return pivot_value_new_text (ctables_summary_function_label__ (
+                                   function, weighting, area));
+}
+\f
+/* CTABLES summaries. */
+
+struct ctables_summary_spec
+  {
+    /* The calculation to be performed.
+
+       'function' is the function to calculate.  'weighted' specifies whether
+       to use weighted or unweighted data (for functions that do not support a
+       choice, it must be true).  'calc_area' is the area over which the
+       calculation takes place (for functions that target only an individual
+       cell, it must be 0).  For CTSF_PTILE only, 'percentile' is the
+       percentile between 0 and 100 (for other functions it must be 0). */
+    enum ctables_summary_function function;
+    enum ctables_weighting weighting;
+    enum ctables_area_type calc_area;
+    double percentile;          /* CTSF_PTILE only. */
+
+    /* How to display the result of the calculation.
+
+       'label' is a user-specified label, NULL if the user didn't specify
+       one.
+
+       'user_area' is usually the same as 'calc_area', but when category labels
+       are rotated from one axis to another it swaps rows and columns.
+
+       'format' is the format for displaying the output.  If
+       'is_ctables_format' is true, then 'format.type' is one of the special
+       CTEF_* formats instead of the standard ones. */
+    char *label;
+    enum ctables_area_type user_area;
+    struct fmt_spec format;
+    bool is_ctables_format;       /* Is 'format' one of CTEF_*? */
+
+    size_t axis_idx;            /* Leaf index if summary dimension in use. */
+    size_t sum_var_idx;         /* Offset into 'sums' in ctables_area. */
+  };
+
+static void
+ctables_summary_spec_clone (struct ctables_summary_spec *dst,
+                            const struct ctables_summary_spec *src)
+{
+  *dst = *src;
+  dst->label = xstrdup_if_nonnull (src->label);
+}
+
+static void
+ctables_summary_spec_uninit (struct ctables_summary_spec *s)
+{
+  if (s)
+    free (s->label);
+}
+\f
+/* Collections of summary functions. */
+
+struct ctables_summary_spec_set
+  {
+    struct ctables_summary_spec *specs;
+    size_t n;
+    size_t allocated;
+
+    /* The variable to which the summary specs are applied. */
+    struct variable *var;
+
+    /* Whether the variable to which the summary specs are applied is a scale
+       variable for the purpose of summarization.
+
+       (VALIDN and TOTALN act differently for summarizing scale and categorical
+       variables.) */
+    bool is_scale;
+
+    /* If any of these optional additional scale variables are missing, then
+       treat 'var' as if it's missing too.  This is for implementing
+       SMISSING=LISTWISE. */
+    struct variable **listwise_vars;
+    size_t n_listwise_vars;
+  };
+
+static void
+ctables_summary_spec_set_clone (struct ctables_summary_spec_set *dst,
+                                const struct ctables_summary_spec_set *src)
+{
+  struct ctables_summary_spec *specs
+    = (src->n ? xnmalloc (src->n, sizeof *specs) : NULL);
+  for (size_t i = 0; i < src->n; i++)
+    ctables_summary_spec_clone (&specs[i], &src->specs[i]);
+
+  *dst = (struct ctables_summary_spec_set) {
+    .specs = specs,
+    .n = src->n,
+    .allocated = src->n,
+    .var = src->var,
+    .is_scale = src->is_scale,
+  };
+}
+
+static void
+ctables_summary_spec_set_uninit (struct ctables_summary_spec_set *set)
+{
+  for (size_t i = 0; i < set->n; i++)
+    ctables_summary_spec_uninit (&set->specs[i]);
+  free (set->listwise_vars);
+  free (set->specs);
+}
+
+static bool
+is_listwise_missing (const struct ctables_summary_spec_set *specs,
+                     const struct ccase *c)
+{
+  for (size_t i = 0; i < specs->n_listwise_vars; i++)
+    {
+      const struct variable *var = specs->listwise_vars[i];
+      if (var_is_num_missing (var, case_num (c, var)))
+        return true;
+    }
+
+  return false;
+}
+\f
+/* CTABLES postcompute expressions. */
+
+struct ctables_postcompute
+  {
+    struct hmap_node hmap_node; /* In struct ctables's 'pcompute' hmap. */
+    char *name;                 /* Name, without leading &. */
+
+    struct msg_location *location; /* Location of definition. */
+    struct ctables_pcexpr *expr;
+    char *label;
+    struct ctables_summary_spec_set *specs;
+    bool hide_source_cats;
+  };
+
+struct ctables_pcexpr
+  {
+    /* Precedence table:
+
+       ()
+       **
+       -
+       * /
+       - +
+    */
+    enum ctables_pcexpr_op
+      {
+        /* Terminals. */
+        CTPO_CONSTANT,          /* 5 */
+        CTPO_CAT_NUMBER,        /* [5] */
+        CTPO_CAT_STRING,        /* ["STRING"] */
+        CTPO_CAT_NRANGE,        /* [LO THRU 5] */
+        CTPO_CAT_SRANGE,        /* ["A" THRU "B"] */
+        CTPO_CAT_MISSING,       /* MISSING */
+        CTPO_CAT_OTHERNM,       /* OTHERNM */
+        CTPO_CAT_SUBTOTAL,      /* SUBTOTAL */
+        CTPO_CAT_TOTAL,         /* TOTAL */
+
+        /* Nonterminals. */
+        CTPO_ADD,
+        CTPO_SUB,
+        CTPO_MUL,
+        CTPO_DIV,
+        CTPO_POW,
+        CTPO_NEG,
+      }
+    op;
+
+    union
+      {
+        /* CTPO_CAT_NUMBER. */
+        double number;
+
+        /* CTPO_CAT_STRING, in dictionary encoding. */
+        struct substring string;
+
+        /* CTPO_CAT_NRANGE. */
+        double nrange[2];
+
+        /* CTPO_CAT_SRANGE. */
+        struct substring srange[2];
+
+        /* CTPO_CAT_SUBTOTAL. */
+        size_t subtotal_index;
+
+        /* Two elements: CTPO_ADD, CTPO_SUB, CTPO_MUL, CTPO_DIV, CTPO_POW.
+           One element: CTPO_NEG. */
+        struct ctables_pcexpr *subs[2];
+      };
+
+    /* Source location. */
+    struct msg_location *location;
+  };
+
+static struct ctables_postcompute *ctables_find_postcompute (struct ctables *,
+                                                             const char *name);
+
+static struct ctables_pcexpr *ctables_pcexpr_allocate_binary (
+  enum ctables_pcexpr_op, struct ctables_pcexpr *sub0,
+  struct ctables_pcexpr *sub1);
+
+typedef struct ctables_pcexpr *parse_recursively_func (struct lexer *,
+                                                       struct dictionary *);
+
+static void
+ctables_pcexpr_destroy (struct ctables_pcexpr *e)
+{
+  if (e)
+    {
+      switch (e->op)
+        {
+        case CTPO_CAT_STRING:
+          ss_dealloc (&e->string);
+          break;
+
+        case CTPO_CAT_SRANGE:
+          for (size_t i = 0; i < 2; i++)
+            ss_dealloc (&e->srange[i]);
+          break;
+
+        case CTPO_ADD:
+        case CTPO_SUB:
+        case CTPO_MUL:
+        case CTPO_DIV:
+        case CTPO_POW:
+        case CTPO_NEG:
+          for (size_t i = 0; i < 2; i++)
+            ctables_pcexpr_destroy (e->subs[i]);
+          break;
+
+        case CTPO_CONSTANT:
+        case CTPO_CAT_NUMBER:
+        case CTPO_CAT_NRANGE:
+        case CTPO_CAT_MISSING:
+        case CTPO_CAT_OTHERNM:
+        case CTPO_CAT_SUBTOTAL:
+        case CTPO_CAT_TOTAL:
+          break;
+        }
+
+      msg_location_destroy (e->location);
+      free (e);
+    }
+}
+
+static struct ctables_pcexpr *
+ctables_pcexpr_allocate_binary (enum ctables_pcexpr_op op,
+                                struct ctables_pcexpr *sub0,
+                                struct ctables_pcexpr *sub1)
+{
+  struct ctables_pcexpr *e = xmalloc (sizeof *e);
+  *e = (struct ctables_pcexpr) {
+    .op = op,
+    .subs = { sub0, sub1 },
+    .location = msg_location_merged (sub0->location, sub1->location),
+  };
+  return e;
+}
+
+/* How to parse an operator. */
+struct operator
+  {
+    enum token_type token;
+    enum ctables_pcexpr_op op;
+  };
+
+static const struct operator *
+ctables_pcexpr_match_operator (struct lexer *lexer,
+                              const struct operator ops[], size_t n_ops)
+{
+  for (const struct operator *op = ops; op < ops + n_ops; op++)
+    if (lex_token (lexer) == op->token)
+      {
+        if (op->token != T_NEG_NUM)
+          lex_get (lexer);
+
+        return op;
+      }
+
+  return NULL;
+}
+
+static struct ctables_pcexpr *
+ctables_pcexpr_parse_binary_operators__ (
+  struct lexer *lexer, struct dictionary *dict,
+  const struct operator ops[], size_t n_ops,
+  parse_recursively_func *parse_next_level,
+  const char *chain_warning, struct ctables_pcexpr *lhs)
+{
+  for (int op_count = 0; ; op_count++)
+    {
+      const struct operator *op
+        = ctables_pcexpr_match_operator (lexer, ops, n_ops);
+      if (!op)
+        {
+          if (op_count > 1 && chain_warning)
+            msg_at (SW, lhs->location, "%s", chain_warning);
+
+          return lhs;
+        }
+
+      struct ctables_pcexpr *rhs = parse_next_level (lexer, dict);
+      if (!rhs)
+        {
+          ctables_pcexpr_destroy (lhs);
+          return NULL;
+        }
+
+      lhs = ctables_pcexpr_allocate_binary (op->op, lhs, rhs);
+    }
+}
+
+static struct ctables_pcexpr *
+ctables_pcexpr_parse_binary_operators (
+  struct lexer *lexer, struct dictionary *dict,
+  const struct operator ops[], size_t n_ops,
+  parse_recursively_func *parse_next_level, const char *chain_warning)
+{
+  struct ctables_pcexpr *lhs = parse_next_level (lexer, dict);
+  if (!lhs)
+    return NULL;
+
+  return ctables_pcexpr_parse_binary_operators__ (lexer, dict, ops, n_ops,
+                                                 parse_next_level,
+                                                 chain_warning, lhs);
+}
+
+static struct ctables_pcexpr *ctables_pcexpr_parse_add (struct lexer *,
+                                                        struct dictionary *);
+
+static struct ctables_pcexpr
+ctpo_cat_nrange (double low, double high)
+{
+  return (struct ctables_pcexpr) {
+    .op = CTPO_CAT_NRANGE,
+    .nrange = { low, high },
+  };
+}
+
+static struct ctables_pcexpr
+ctpo_cat_srange (struct substring low, struct substring high)
+{
+  return (struct ctables_pcexpr) {
+    .op = CTPO_CAT_SRANGE,
+    .srange = { low, high },
+  };
+}
+
+static struct substring
+parse_substring (struct lexer *lexer, struct dictionary *dict)
+{
+  struct substring s = recode_substring_pool (
+    dict_get_encoding (dict), "UTF-8", lex_tokss (lexer), NULL);
+  ss_rtrim (&s, ss_cstr (" "));
+  lex_get (lexer);
+  return s;
+}
+
+static struct ctables_pcexpr *
+ctables_pcexpr_parse_primary (struct lexer *lexer, struct dictionary *dict)
+{
+  int start_ofs = lex_ofs (lexer);
+  struct ctables_pcexpr e;
+  if (lex_is_number (lexer))
+    {
+      e = (struct ctables_pcexpr) { .op = CTPO_CONSTANT,
+                                    .number = lex_number (lexer) };
+      lex_get (lexer);
+    }
+  else if (lex_match_id (lexer, "MISSING"))
+    e = (struct ctables_pcexpr) { .op = CTPO_CAT_MISSING };
+  else if (lex_match_id (lexer, "OTHERNM"))
+    e = (struct ctables_pcexpr) { .op = CTPO_CAT_OTHERNM };
+  else if (lex_match_id (lexer, "TOTAL"))
+    e = (struct ctables_pcexpr) { .op = CTPO_CAT_TOTAL };
+  else if (lex_match_id (lexer, "SUBTOTAL"))
+    {
+      size_t subtotal_index = 0;
+      if (lex_match (lexer, T_LBRACK))
+        {
+          if (!lex_force_int_range (lexer, "SUBTOTAL", 1, LONG_MAX))
+            return NULL;
+          subtotal_index = lex_integer (lexer);
+          lex_get (lexer);
+          if (!lex_force_match (lexer, T_RBRACK))
+            return NULL;
+        }
+      e = (struct ctables_pcexpr) { .op = CTPO_CAT_SUBTOTAL,
+                                    .subtotal_index = subtotal_index };
+    }
+  else if (lex_match (lexer, T_LBRACK))
+    {
+      if (lex_match_id (lexer, "LO"))
+        {
+          if (!lex_force_match_id (lexer, "THRU"))
+            return false;
+
+          if (lex_is_string (lexer))
+            {
+              struct substring low = { .string = NULL };
+              struct substring high = parse_substring (lexer, dict);
+              e = ctpo_cat_srange (low, high);
+            }
+          else
+            {
+              if (!lex_force_num (lexer))
+                return false;
+              e = ctpo_cat_nrange (-DBL_MAX, lex_number (lexer));
+              lex_get (lexer);
+            }
+        }
+      else if (lex_is_number (lexer))
+        {
+          double number = lex_number (lexer);
+          lex_get (lexer);
+          if (lex_match_id (lexer, "THRU"))
+            {
+              if (lex_match_id (lexer, "HI"))
+                e = ctpo_cat_nrange (number, DBL_MAX);
+              else
+                {
+                  if (!lex_force_num (lexer))
+                    return false;
+                  e = ctpo_cat_nrange (number, lex_number (lexer));
+                  lex_get (lexer);
+                }
+            }
+          else
+            e = (struct ctables_pcexpr) { .op = CTPO_CAT_NUMBER,
+                                          .number = number };
+        }
+      else if (lex_is_string (lexer))
+        {
+          struct substring s = parse_substring (lexer, dict);
+
+          if (lex_match_id (lexer, "THRU"))
+            {
+              struct substring high;
+
+              if (lex_match_id (lexer, "HI"))
+                high = (struct substring) { .string = NULL };
+              else
+                {
+                  if (!lex_force_string (lexer))
+                    {
+                      ss_dealloc (&s);
+                      return false;
+                    }
+                  high = parse_substring (lexer, dict);
+                }
+
+              e = ctpo_cat_srange (s, high);
+            }
+          else
+            e = (struct ctables_pcexpr) { .op = CTPO_CAT_STRING, .string = s };
+        }
+      else
+        {
+          lex_error (lexer, NULL);
+          return NULL;
+        }
+
+      if (!lex_force_match (lexer, T_RBRACK))
+        {
+          if (e.op == CTPO_CAT_STRING)
+            ss_dealloc (&e.string);
+          else if (e.op == CTPO_CAT_SRANGE)
+            {
+              ss_dealloc (&e.srange[0]);
+              ss_dealloc (&e.srange[1]);
+            }
+          return NULL;
+        }
+    }
+  else if (lex_match (lexer, T_LPAREN))
+    {
+      struct ctables_pcexpr *ep = ctables_pcexpr_parse_add (lexer, dict);
+      if (!ep)
+        return NULL;
+      if (!lex_force_match (lexer, T_RPAREN))
+        {
+          ctables_pcexpr_destroy (ep);
+          return NULL;
+        }
+      return ep;
+    }
+  else
+    {
+      lex_error (lexer, NULL);
+      return NULL;
+    }
+
+  e.location = lex_ofs_location (lexer, start_ofs, lex_ofs (lexer) - 1);
+  return xmemdup (&e, sizeof e);
+}
+
+static struct ctables_pcexpr *
+ctables_pcexpr_allocate_neg (struct ctables_pcexpr *sub,
+                             struct lexer *lexer, int start_ofs)
+{
+  struct ctables_pcexpr *e = xmalloc (sizeof *e);
+  *e = (struct ctables_pcexpr) {
+    .op = CTPO_NEG,
+    .subs = { sub },
+    .location = lex_ofs_location (lexer, start_ofs, lex_ofs (lexer) - 1),
+  };
+  return e;
+}
+
+static struct ctables_pcexpr *
+ctables_pcexpr_parse_exp (struct lexer *lexer, struct dictionary *dict)
+{
+  static const struct operator op = { T_EXP, CTPO_POW };
+
+  const char *chain_warning =
+    _("The exponentiation operator (`**') is left-associative: "
+      "`a**b**c' equals `(a**b)**c', not `a**(b**c)'.  "
+      "To disable this warning, insert parentheses.");
+
+  if (lex_token (lexer) != T_NEG_NUM || lex_next_token (lexer, 1) != T_EXP)
+    return ctables_pcexpr_parse_binary_operators (lexer, dict, &op, 1,
+                                                  ctables_pcexpr_parse_primary,
+                                                  chain_warning);
+
+  /* Special case for situations like "-5**6", which must be parsed as
+     -(5**6). */
+
+  int start_ofs = lex_ofs (lexer);
+  struct ctables_pcexpr *lhs = xmalloc (sizeof *lhs);
+  *lhs = (struct ctables_pcexpr) {
+    .op = CTPO_CONSTANT,
+    .number = -lex_tokval (lexer),
+    .location = lex_ofs_location (lexer, start_ofs, lex_ofs (lexer)),
+  };
+  lex_get (lexer);
+
+  struct ctables_pcexpr *node = ctables_pcexpr_parse_binary_operators__ (
+    lexer, dict, &op, 1,
+    ctables_pcexpr_parse_primary, chain_warning, lhs);
+  if (!node)
+    return NULL;
+
+  return ctables_pcexpr_allocate_neg (node, lexer, start_ofs);
+}
+
+/* Parses the unary minus level. */
+static struct ctables_pcexpr *
+ctables_pcexpr_parse_neg (struct lexer *lexer, struct dictionary *dict)
+{
+  int start_ofs = lex_ofs (lexer);
+  if (!lex_match (lexer, T_DASH))
+    return ctables_pcexpr_parse_exp (lexer, dict);
+
+  struct ctables_pcexpr *inner = ctables_pcexpr_parse_neg (lexer, dict);
+  if (!inner)
+    return NULL;
+
+  return ctables_pcexpr_allocate_neg (inner, lexer, start_ofs);
+}
+
+/* Parses the multiplication and division level. */
+static struct ctables_pcexpr *
+ctables_pcexpr_parse_mul (struct lexer *lexer, struct dictionary *dict)
+{
+  static const struct operator ops[] =
+    {
+      { T_ASTERISK, CTPO_MUL },
+      { T_SLASH, CTPO_DIV },
+    };
+
+  return ctables_pcexpr_parse_binary_operators (lexer, dict, ops,
+                                               sizeof ops / sizeof *ops,
+                                               ctables_pcexpr_parse_neg, NULL);
+}
+
+/* Parses the addition and subtraction level. */
+static struct ctables_pcexpr *
+ctables_pcexpr_parse_add (struct lexer *lexer, struct dictionary *dict)
+{
+  static const struct operator ops[] =
+    {
+      { T_PLUS, CTPO_ADD },
+      { T_DASH, CTPO_SUB },
+      { T_NEG_NUM, CTPO_ADD },
+    };
+
+  return ctables_pcexpr_parse_binary_operators (lexer, dict,
+                                               ops, sizeof ops / sizeof *ops,
+                                               ctables_pcexpr_parse_mul, NULL);
+}
+\f
+/* CTABLES axis expressions. */
+
+/* CTABLES has a number of extra formats that we implement via custom
+   currency specifications on an alternate fmt_settings. */
+#define CTEF_NEGPAREN FMT_CCA
+#define CTEF_NEQUAL   FMT_CCB
+#define CTEF_PAREN    FMT_CCC
+#define CTEF_PCTPAREN FMT_CCD
+
+enum ctables_summary_variant
+  {
+    CSV_CELL,
+    CSV_TOTAL
+#define N_CSVS 2
+  };
+
+struct ctables_axis
+  {
+    enum ctables_axis_op
+      {
+        /* Terminals. */
+        CTAO_VAR,
+
+        /* Nonterminals. */
+        CTAO_STACK,             /* + */
+        CTAO_NEST,              /* > */
+      }
+    op;
+
+    union
+      {
+        /* Terminals. */
+        struct
+          {
+            struct variable *var;
+            bool scale;
+            struct ctables_summary_spec_set specs[N_CSVS];
+          };
+
+        /* Nonterminals. */
+        struct ctables_axis *subs[2];
+      };
+
+    struct msg_location *loc;
+  };
+
+static void
+ctables_axis_destroy (struct ctables_axis *axis)
+{
+  if (!axis)
+    return;
+
+  switch (axis->op)
+    {
+    case CTAO_VAR:
+      for (size_t i = 0; i < N_CSVS; i++)
+        ctables_summary_spec_set_uninit (&axis->specs[i]);
+      break;
+
+    case CTAO_STACK:
+    case CTAO_NEST:
+      ctables_axis_destroy (axis->subs[0]);
+      ctables_axis_destroy (axis->subs[1]);
+      break;
+    }
+  msg_location_destroy (axis->loc);
+  free (axis);
+}
+
+static struct ctables_axis *
+ctables_axis_new_nonterminal (enum ctables_axis_op op,
+                              struct ctables_axis *sub0,
+                              struct ctables_axis *sub1,
+                              struct lexer *lexer, int start_ofs)
+{
+  struct ctables_axis *axis = xmalloc (sizeof *axis);
+  *axis = (struct ctables_axis) {
+    .op = op,
+    .subs = { sub0, sub1 },
+    .loc = lex_ofs_location (lexer, start_ofs, lex_ofs (lexer) - 1),
+  };
+  return axis;
+}
+
+struct ctables_axis_parse_ctx
+  {
+    struct lexer *lexer;
+    struct dictionary *dict;
+  };
+
+static struct pivot_value *
+ctables_summary_label (const struct ctables_summary_spec *spec, double cilevel)
+{
+  if (!spec->label)
+    return ctables_summary_function_label (spec->function, spec->weighting,
+                                           spec->user_area, spec->percentile);
+  else
+    {
+      struct substring in = ss_cstr (spec->label);
+      struct substring target = ss_cstr (")CILEVEL");
+
+      struct string out = DS_EMPTY_INITIALIZER;
+      for (;;)
+        {
+          size_t chunk = ss_find_substring (in, target);
+          ds_put_substring (&out, ss_head (in, chunk));
+          ss_advance (&in, chunk);
+          if (!in.length)
+            return pivot_value_new_user_text_nocopy (ds_steal_cstr (&out));
+
+          ss_advance (&in, target.length);
+          ds_put_format (&out, "%g", cilevel);
+        }
+    }
+}
+
+static bool
+add_summary_spec (struct ctables_axis *axis,
+                  enum ctables_summary_function function,
+                  enum ctables_weighting weighting,
+                  enum ctables_area_type area, double percentile,
+                  const char *label, const struct fmt_spec *format,
+                  bool is_ctables_format, const struct msg_location *loc,
+                  enum ctables_summary_variant sv)
+{
+  if (axis->op == CTAO_VAR)
+    {
+      char function_name[128];
+      ctables_summary_function_name (function, weighting, area,
+                                     function_name, sizeof function_name);
+      const char *var_name = var_get_name (axis->var);
+      switch (ctables_function_availability (function))
+        {
+#if 0
+        case CTFA_MRSETS:
+          msg_at (SE, loc, _("Summary function %s applies only to multiple "
+                             "response sets."), function_name);
+          msg_at (SN, axis->loc, _("'%s' is not a multiple response set."),
+                  var_name);
+          return false;
+#endif
+
+        case CTFA_SCALE:
+          if (!axis->scale && sv != CSV_TOTAL)
+            {
+              msg_at (SE, loc,
+                      _("Summary function %s applies only to scale variables."),
+                      function_name);
+              msg_at (SN, axis->loc, _("'%s' is not a scale variable."),
+                      var_name);
+              return false;
+            }
+          break;
+
+        case CTFA_ALL:
+          break;
+        }
+
+      struct ctables_summary_spec_set *set = &axis->specs[sv];
+      if (set->n >= set->allocated)
+        set->specs = x2nrealloc (set->specs, &set->allocated,
+                                 sizeof *set->specs);
+
+      struct ctables_summary_spec *dst = &set->specs[set->n++];
+      *dst = (struct ctables_summary_spec) {
+        .function = function,
+        .weighting = weighting,
+        .calc_area = area,
+        .user_area = area,
+        .percentile = percentile,
+        .label = xstrdup_if_nonnull (label),
+        .format = (format ? *format
+                   : ctables_summary_default_format (function, axis->var)),
+        .is_ctables_format = is_ctables_format,
+      };
+      return true;
+    }
+  else
+    {
+      for (size_t i = 0; i < 2; i++)
+        if (!add_summary_spec (axis->subs[i], function, weighting, area,
+                               percentile, label, format, is_ctables_format,
+                               loc, sv))
+          return false;
+      return true;
+    }
+}
+
+static struct ctables_axis *ctables_axis_parse_stack (
+  struct ctables_axis_parse_ctx *);
+
+static struct ctables_axis *
+ctables_axis_parse_primary (struct ctables_axis_parse_ctx *ctx)
+{
+  if (lex_match (ctx->lexer, T_LPAREN))
+    {
+      struct ctables_axis *sub = ctables_axis_parse_stack (ctx);
+      if (!sub || !lex_force_match (ctx->lexer, T_RPAREN))
+        {
+          ctables_axis_destroy (sub);
+          return NULL;
+        }
+      return sub;
+    }
+
+  if (!lex_force_id (ctx->lexer))
+    return NULL;
+
+  if (lex_tokcstr (ctx->lexer)[0] == '$')
+    {
+      lex_error (ctx->lexer,
+                 _("Multiple response set support not implemented."));
+      return NULL;
+    }
+
+  int start_ofs = lex_ofs (ctx->lexer);
+  struct variable *var = parse_variable (ctx->lexer, ctx->dict);
+  if (!var)
+    return NULL;
+
+  struct ctables_axis *axis = xmalloc (sizeof *axis);
+  *axis = (struct ctables_axis) { .op = CTAO_VAR, .var = var };
+
+  axis->scale = (lex_match_phrase (ctx->lexer, "[S]") ? true
+                 : lex_match_phrase (ctx->lexer, "[C]") ? false
+                 : var_get_measure (var) == MEASURE_SCALE);
+  axis->loc = lex_ofs_location (ctx->lexer, start_ofs,
+                                lex_ofs (ctx->lexer) - 1);
+  if (axis->scale && var_is_alpha (var))
+    {
+      msg_at (SE, axis->loc, _("Cannot use string variable %s as a scale "
+                               "variable."),
+              var_get_name (var));
+      ctables_axis_destroy (axis);
+      return NULL;
+    }
+
+  return axis;
+}
+
+static bool
+has_digit (const char *s)
+{
+  return s[strcspn (s, "0123456789")] != '\0';
+}
+
+static bool
+parse_ctables_format_specifier (struct lexer *lexer, struct fmt_spec *format,
+                                bool *is_ctables_format)
+{
+  char type[FMT_TYPE_LEN_MAX + 1];
+  if (!parse_abstract_format_specifier__ (lexer, type, &format->w, &format->d))
+    return false;
+
+  if (!strcasecmp (type, "NEGPAREN"))
+    format->type = CTEF_NEGPAREN;
+  else if (!strcasecmp (type, "NEQUAL"))
+    format->type = CTEF_NEQUAL;
+  else if (!strcasecmp (type, "PAREN"))
+    format->type = CTEF_PAREN;
+  else if (!strcasecmp (type, "PCTPAREN"))
+    format->type = CTEF_PCTPAREN;
+  else
+    {
+      *is_ctables_format = false;
+      return (parse_format_specifier (lexer, format)
+              && fmt_check_output (format)
+              && fmt_check_type_compat (format, VAL_NUMERIC));
+    }
+
+  lex_get (lexer);
+  if (format->w < 2)
+    {
+      lex_next_error (lexer, -1, -1,
+                      _("Output format %s requires width 2 or greater."), type);
+      return false;
+    }
+  else if (format->d > format->w - 1)
+    {
+      lex_next_error (lexer, -1, -1, _("Output format %s requires width "
+                                       "greater than decimals."), type);
+      return false;
+    }
+  else
+    {
+      *is_ctables_format = true;
+      return true;
+    }
+}
+
+static struct ctables_axis *
+ctables_axis_parse_postfix (struct ctables_axis_parse_ctx *ctx)
+{
+  struct ctables_axis *sub = ctables_axis_parse_primary (ctx);
+  if (!sub || !lex_match (ctx->lexer, T_LBRACK))
+    return sub;
+
+  enum ctables_summary_variant sv = CSV_CELL;
+  for (;;)
+    {
+      int start_ofs = lex_ofs (ctx->lexer);
+
+      /* Parse function. */
+      enum ctables_summary_function function;
+      enum ctables_weighting weighting;
+      enum ctables_area_type area;
+      if (!parse_ctables_summary_function (ctx->lexer, &function, &weighting,
+                                           &area))
+        goto error;
+
+      /* Parse percentile. */
+      double percentile = 0;
+      if (function == CTSF_PTILE)
+        {
+          if (!lex_force_num_range_closed (ctx->lexer, "PTILE", 0, 100))
+            goto error;
+          percentile = lex_number (ctx->lexer);
+          lex_get (ctx->lexer);
+        }
+
+      /* Parse label. */
+      char *label = NULL;
+      if (lex_is_string (ctx->lexer))
+        {
+          label = ss_xstrdup (lex_tokss (ctx->lexer));
+          lex_get (ctx->lexer);
+        }
+
+      /* Parse format. */
+      struct fmt_spec format;
+      const struct fmt_spec *formatp;
+      bool is_ctables_format = false;
+      if (lex_token (ctx->lexer) == T_ID
+          && has_digit (lex_tokcstr (ctx->lexer)))
+        {
+          if (!parse_ctables_format_specifier (ctx->lexer, &format,
+                                               &is_ctables_format))
+            {
+              free (label);
+              goto error;
+            }
+          formatp = &format;
+        }
+      else
+        formatp = NULL;
+
+      struct msg_location *loc = lex_ofs_location (ctx->lexer, start_ofs,
+                                                   lex_ofs (ctx->lexer) - 1);
+      add_summary_spec (sub, function, weighting, area, percentile, label,
+                        formatp, is_ctables_format, loc, sv);
+      free (label);
+      msg_location_destroy (loc);
+
+      lex_match (ctx->lexer, T_COMMA);
+      if (sv == CSV_CELL && lex_match_id (ctx->lexer, "TOTALS"))
+        {
+          if (!lex_force_match (ctx->lexer, T_LBRACK))
+            goto error;
+          sv = CSV_TOTAL;
+        }
+      else if (lex_match (ctx->lexer, T_RBRACK))
+        {
+          if (sv == CSV_TOTAL && !lex_force_match (ctx->lexer, T_RBRACK))
+            goto error;
+          return sub;
+        }
+    }
+
+error:
+  ctables_axis_destroy (sub);
+  return NULL;
+}
+
+static const struct ctables_axis *
+find_scale (const struct ctables_axis *axis)
+{
+  if (!axis)
+    return NULL;
+  else if (axis->op == CTAO_VAR)
+    return axis->scale ? axis : NULL;
+  else
+    {
+      for (size_t i = 0; i < 2; i++)
+        {
+          const struct ctables_axis *scale = find_scale (axis->subs[i]);
+          if (scale)
+            return scale;
+        }
+      return NULL;
+    }
+}
+
+static const struct ctables_axis *
+find_categorical_summary_spec (const struct ctables_axis *axis)
+{
+  if (!axis)
+    return NULL;
+  else if (axis->op == CTAO_VAR)
+    return !axis->scale && axis->specs[CSV_CELL].n ? axis : NULL;
+  else
+    {
+      for (size_t i = 0; i < 2; i++)
+        {
+          const struct ctables_axis *sum
+            = find_categorical_summary_spec (axis->subs[i]);
+          if (sum)
+            return sum;
+        }
+      return NULL;
+    }
+}
+
+static struct ctables_axis *
+ctables_axis_parse_nest (struct ctables_axis_parse_ctx *ctx)
+{
+  int start_ofs = lex_ofs (ctx->lexer);
+  struct ctables_axis *lhs = ctables_axis_parse_postfix (ctx);
+  if (!lhs)
+    return NULL;
+
+  while (lex_match (ctx->lexer, T_GT))
+    {
+      struct ctables_axis *rhs = ctables_axis_parse_postfix (ctx);
+      if (!rhs)
+        {
+          ctables_axis_destroy (lhs);
+          return NULL;
+        }
+
+      struct ctables_axis *nest = ctables_axis_new_nonterminal (
+        CTAO_NEST, lhs, rhs, ctx->lexer, start_ofs);
+
+      const struct ctables_axis *outer_scale = find_scale (lhs);
+      const struct ctables_axis *inner_scale = find_scale (rhs);
+      if (outer_scale && inner_scale)
+        {
+          msg_at (SE, nest->loc, _("Cannot nest scale variables."));
+          msg_at (SN, outer_scale->loc, _("This is an outer scale variable."));
+          msg_at (SN, inner_scale->loc, _("This is an inner scale variable."));
+          ctables_axis_destroy (nest);
+          return NULL;
+        }
+
+      const struct ctables_axis *outer_sum = find_categorical_summary_spec (lhs);
+      if (outer_sum)
+        {
+          msg_at (SE, nest->loc,
+                  _("Summaries may only be requested for categorical variables "
+                    "at the innermost nesting level."));
+          msg_at (SN, outer_sum->loc,
+                  _("This outer categorical variable has a summary."));
+          ctables_axis_destroy (nest);
+          return NULL;
+        }
+
+      lhs = nest;
+    }
+
+  return lhs;
+}
+
+static struct ctables_axis *
+ctables_axis_parse_stack (struct ctables_axis_parse_ctx *ctx)
+{
+  int start_ofs = lex_ofs (ctx->lexer);
+  struct ctables_axis *lhs = ctables_axis_parse_nest (ctx);
+  if (!lhs)
+    return NULL;
+
+  while (lex_match (ctx->lexer, T_PLUS))
+    {
+      struct ctables_axis *rhs = ctables_axis_parse_nest (ctx);
+      if (!rhs)
+        {
+          ctables_axis_destroy (lhs);
+          return NULL;
+        }
+
+      lhs = ctables_axis_new_nonterminal (CTAO_STACK, lhs, rhs,
+                                          ctx->lexer, start_ofs);
+    }
+
+  return lhs;
+}
+
+static bool
+ctables_axis_parse (struct lexer *lexer, struct dictionary *dict,
+                    struct ctables_axis **axisp)
+{
+  *axisp = NULL;
+  if (lex_token (lexer) == T_BY
+      || lex_token (lexer) == T_SLASH
+      || lex_token (lexer) == T_ENDCMD)
+    return true;
+
+  struct ctables_axis_parse_ctx ctx = {
+    .lexer = lexer,
+    .dict = dict,
+  };
+  *axisp = ctables_axis_parse_stack (&ctx);
+  return *axisp;
+}
+\f
+/* CTABLES categories. */
+
+struct ctables_categories
+  {
+    size_t n_refs;
+    struct ctables_category *cats;
+    size_t n_cats;
+    bool show_empty;
+  };
+
+struct ctables_category
+  {
+    enum ctables_category_type
+      {
+        /* Explicit category lists. */
+        CCT_NUMBER,
+        CCT_STRING,
+        CCT_NRANGE,             /* Numerical range. */
+        CCT_SRANGE,             /* String range. */
+        CCT_MISSING,
+        CCT_OTHERNM,
+        CCT_POSTCOMPUTE,
+
+        /* Totals and subtotals. */
+        CCT_SUBTOTAL,
+        CCT_TOTAL,
+
+        /* Implicit category lists. */
+        CCT_VALUE,
+        CCT_LABEL,
+        CCT_FUNCTION,
+
+        /* For contributing to TOTALN. */
+        CCT_EXCLUDED_MISSING,
+      }
+    type;
+
+    struct ctables_category *subtotal;
+
+    bool hide;
+
+    union
+      {
+        double number;           /* CCT_NUMBER. */
+        struct substring string; /* CCT_STRING, in dictionary encoding. */
+        double nrange[2];        /* CCT_NRANGE. */
+        struct substring srange[2]; /* CCT_SRANGE. */
+
+        struct
+          {
+            char *total_label;      /* CCT_SUBTOTAL, CCT_TOTAL. */
+            bool hide_subcategories; /* CCT_SUBTOTAL. */
+          };
+
+        /* CCT_POSTCOMPUTE. */
+        struct
+          {
+            const struct ctables_postcompute *pc;
+            enum fmt_type parse_format;
+          };
+
+        /* CCT_VALUE, CCT_LABEL, CCT_FUNCTION. */
+        struct
+          {
+            bool include_missing;
+            bool sort_ascending;
+
+            /* CCT_FUNCTION. */
+            enum ctables_summary_function sort_function;
+            enum ctables_weighting weighting;
+            enum ctables_area_type area;
+            struct variable *sort_var;
+            double percentile;
+          };
+      };
+
+    /* Source location.  This is null for CCT_TOTAL, CCT_VALUE, CCT_LABEL,
+       CCT_FUNCTION, CCT_EXCLUDED_MISSING. */
+    struct msg_location *location;
+  };
+
+static void
+ctables_category_uninit (struct ctables_category *cat)
+{
+  if (!cat)
+    return;
+
+  msg_location_destroy (cat->location);
+  switch (cat->type)
+    {
+    case CCT_NUMBER:
+    case CCT_NRANGE:
+    case CCT_MISSING:
+    case CCT_OTHERNM:
+    case CCT_POSTCOMPUTE:
+      break;
+
+    case CCT_STRING:
+      ss_dealloc (&cat->string);
+      break;
+
+    case CCT_SRANGE:
+      ss_dealloc (&cat->srange[0]);
+      ss_dealloc (&cat->srange[1]);
+      break;
+
+    case CCT_SUBTOTAL:
+    case CCT_TOTAL:
+      free (cat->total_label);
+      break;
+
+    case CCT_VALUE:
+    case CCT_LABEL:
+    case CCT_FUNCTION:
+      break;
+
+    case CCT_EXCLUDED_MISSING:
+      break;
+    }
+}
+
+static bool
+nullable_substring_equal (const struct substring *a,
+                          const struct substring *b)
+{
+  return !a->string ? !b->string : b->string && ss_equals (*a, *b);
+}
+
+static bool
+ctables_category_equal (const struct ctables_category *a,
+                        const struct ctables_category *b)
+{
+  if (a->type != b->type)
+    return false;
+
+  switch (a->type)
+    {
+    case CCT_NUMBER:
+      return a->number == b->number;
+
+    case CCT_STRING:
+      return ss_equals (a->string, b->string);
+
+    case CCT_NRANGE:
+      return a->nrange[0] == b->nrange[0] && a->nrange[1] == b->nrange[1];
+
+    case CCT_SRANGE:
+      return (nullable_substring_equal (&a->srange[0], &b->srange[0])
+              && nullable_substring_equal (&a->srange[1], &b->srange[1]));
+
+    case CCT_MISSING:
+    case CCT_OTHERNM:
+      return true;
+
+    case CCT_POSTCOMPUTE:
+      return a->pc == b->pc;
+
+    case CCT_SUBTOTAL:
+    case CCT_TOTAL:
+      return !strcmp (a->total_label, b->total_label);
+
+    case CCT_VALUE:
+    case CCT_LABEL:
+    case CCT_FUNCTION:
+      return (a->include_missing == b->include_missing
+              && a->sort_ascending == b->sort_ascending
+              && a->sort_function == b->sort_function
+              && a->sort_var == b->sort_var
+              && a->percentile == b->percentile);
+
+    case CCT_EXCLUDED_MISSING:
+      return true;
+    }
+
+  NOT_REACHED ();
+}
+
+static void
+ctables_categories_unref (struct ctables_categories *c)
+{
+  if (!c)
+    return;
+
+  assert (c->n_refs > 0);
+  if (--c->n_refs)
+    return;
+
+  for (size_t i = 0; i < c->n_cats; i++)
+    ctables_category_uninit (&c->cats[i]);
+  free (c->cats);
+  free (c);
+}
+
+static bool
+ctables_categories_equal (const struct ctables_categories *a,
+                          const struct ctables_categories *b)
+{
+  if (a->n_cats != b->n_cats || a->show_empty != b->show_empty)
+    return false;
+
+  for (size_t i = 0; i < a->n_cats; i++)
+    if (!ctables_category_equal (&a->cats[i], &b->cats[i]))
+      return false;
+
+  return true;
+}
+
+static struct ctables_category
+cct_nrange (double low, double high)
+{
+  return (struct ctables_category) {
+    .type = CCT_NRANGE,
+    .nrange = { low, high }
+  };
+}
+
+static struct ctables_category
+cct_srange (struct substring low, struct substring high)
+{
+  return (struct ctables_category) {
+    .type = CCT_SRANGE,
+    .srange = { low, high }
+  };
+}
+
+static bool
+ctables_table_parse_subtotal (struct lexer *lexer, bool hide_subcategories,
+                              struct ctables_category *cat)
+{
+  char *total_label;
+  if (lex_match (lexer, T_EQUALS))
+    {
+      if (!lex_force_string (lexer))
+        return false;
+
+      total_label = ss_xstrdup (lex_tokss (lexer));
+      lex_get (lexer);
+    }
+  else
+    total_label = xstrdup (_("Subtotal"));
+
+  *cat = (struct ctables_category) {
+    .type = CCT_SUBTOTAL,
+    .hide_subcategories = hide_subcategories,
+    .total_label = total_label
+  };
+  return true;
+}
+
+static bool
+ctables_table_parse_explicit_category (struct lexer *lexer,
+                                       struct dictionary *dict,
+                                       struct ctables *ct,
+                                       struct ctables_category *cat)
+{
+  if (lex_match_id (lexer, "OTHERNM"))
+    *cat = (struct ctables_category) { .type = CCT_OTHERNM };
+  else if (lex_match_id (lexer, "MISSING"))
+    *cat = (struct ctables_category) { .type = CCT_MISSING };
+  else if (lex_match_id (lexer, "SUBTOTAL"))
+    return ctables_table_parse_subtotal (lexer, false, cat);
+  else if (lex_match_id (lexer, "HSUBTOTAL"))
+    return ctables_table_parse_subtotal (lexer, true, cat);
+  else if (lex_match_id (lexer, "LO"))
+    {
+      if (!lex_force_match_id (lexer, "THRU"))
+        return false;
+      if (lex_is_string (lexer))
+        {
+          struct substring sr0 = { .string = NULL };
+          struct substring sr1 = parse_substring (lexer, dict);
+          *cat = cct_srange (sr0, sr1);
+        }
+      else if (lex_force_num (lexer))
+        {
+          *cat = cct_nrange (-DBL_MAX, lex_number (lexer));
+          lex_get (lexer);
+        }
+      else
+        return false;
+    }
+  else if (lex_is_number (lexer))
+    {
+      double number = lex_number (lexer);
+      lex_get (lexer);
+      if (lex_match_id (lexer, "THRU"))
+        {
+          if (lex_match_id (lexer, "HI"))
+            *cat = cct_nrange (number, DBL_MAX);
+          else
+            {
+              if (!lex_force_num (lexer))
+                return false;
+              *cat = cct_nrange (number, lex_number (lexer));
+              lex_get (lexer);
+            }
+        }
+      else
+        *cat = (struct ctables_category) {
+          .type = CCT_NUMBER,
+          .number = number
+        };
+    }
+  else if (lex_is_string (lexer))
+    {
+      struct substring s = parse_substring (lexer, dict);
+      if (lex_match_id (lexer, "THRU"))
+        {
+          if (lex_match_id (lexer, "HI"))
+            {
+              struct substring sr1 = { .string = NULL };
+              *cat = cct_srange (s, sr1);
+            }
+          else
+            {
+              if (!lex_force_string (lexer))
+                {
+                  ss_dealloc (&s);
+                  return false;
+                }
+              struct substring sr1 = parse_substring (lexer, dict);
+              *cat = cct_srange (s, sr1);
+            }
+        }
+      else
+        *cat = (struct ctables_category) { .type = CCT_STRING, .string = s };
+    }
+  else if (lex_match (lexer, T_AND))
+    {
+      if (!lex_force_id (lexer))
+        return false;
+      struct ctables_postcompute *pc = ctables_find_postcompute (
+        ct, lex_tokcstr (lexer));
+      if (!pc)
+        {
+          struct msg_location *loc = lex_get_location (lexer, -1, 0);
+          msg_at (SE, loc, _("Unknown postcompute &%s."),
+                  lex_tokcstr (lexer));
+          msg_location_destroy (loc);
+          return false;
+        }
+      lex_get (lexer);
+
+      *cat = (struct ctables_category) { .type = CCT_POSTCOMPUTE, .pc = pc };
+    }
+  else
+    {
+      lex_error (lexer, NULL);
+      return false;
+    }
+
+  return true;
+}
+
+static bool
+parse_category_string (struct msg_location *location,
+                       struct substring s, const struct dictionary *dict,
+                       enum fmt_type format, double *n)
+{
+  union value v;
+  char *error = data_in (s, dict_get_encoding (dict), format,
+                         settings_get_fmt_settings (), &v, 0, NULL);
+  if (error)
+    {
+      msg_at (SE, location,
+              _("Failed to parse category specification as format %s: %s."),
+              fmt_name (format), error);
+      free (error);
+      return false;
+    }
+
+  *n = v.f;
+  return true;
+}
+
+static struct ctables_category *
+ctables_find_category_for_postcompute__ (const struct ctables_categories *cats,
+                                         const struct ctables_pcexpr *e)
+{
+  struct ctables_category *best = NULL;
+  size_t n_subtotals = 0;
+  for (size_t i = 0; i < cats->n_cats; i++)
+    {
+      struct ctables_category *cat = &cats->cats[i];
+      switch (e->op)
+        {
+        case CTPO_CAT_NUMBER:
+          if (cat->type == CCT_NUMBER && cat->number == e->number)
+            best = cat;
+          break;
+
+        case CTPO_CAT_STRING:
+          if (cat->type == CCT_STRING && ss_equals (cat->string, e->string))
+            best = cat;
+          break;
+
+        case CTPO_CAT_NRANGE:
+          if (cat->type == CCT_NRANGE
+              && cat->nrange[0] == e->nrange[0]
+              && cat->nrange[1] == e->nrange[1])
+            best = cat;
+          break;
+
+        case CTPO_CAT_SRANGE:
+          if (cat->type == CCT_SRANGE
+              && nullable_substring_equal (&cat->srange[0], &e->srange[0])
+              && nullable_substring_equal (&cat->srange[1], &e->srange[1]))
+            best = cat;
+          break;
+
+        case CTPO_CAT_MISSING:
+          if (cat->type == CCT_MISSING)
+            best = cat;
+          break;
+
+        case CTPO_CAT_OTHERNM:
+          if (cat->type == CCT_OTHERNM)
+            best = cat;
+          break;
+
+        case CTPO_CAT_SUBTOTAL:
+          if (cat->type == CCT_SUBTOTAL)
+            {
+              n_subtotals++;
+              if (e->subtotal_index == n_subtotals)
+                return cat;
+              else if (e->subtotal_index == 0)
+                best = cat;
+            }
+          break;
+
+        case CTPO_CAT_TOTAL:
+          if (cat->type == CCT_TOTAL)
+            return cat;
+          break;
+
+        case CTPO_CONSTANT:
+        case CTPO_ADD:
+        case CTPO_SUB:
+        case CTPO_MUL:
+        case CTPO_DIV:
+        case CTPO_POW:
+        case CTPO_NEG:
+          NOT_REACHED ();
+        }
+    }
+  if (e->op == CTPO_CAT_SUBTOTAL && e->subtotal_index == 0 && n_subtotals > 1)
+    return NULL;
+  return best;
+}
+
+static struct ctables_category *
+ctables_find_category_for_postcompute (const struct dictionary *dict,
+                                       const struct ctables_categories *cats,
+                                       enum fmt_type parse_format,
+                                       const struct ctables_pcexpr *e)
+{
+  if (parse_format != FMT_F)
+    {
+      if (e->op == CTPO_CAT_STRING)
+        {
+          double number;
+          if (!parse_category_string (e->location, e->string, dict,
+                                      parse_format, &number))
+            return NULL;
+
+          struct ctables_pcexpr e2 = {
+            .op = CTPO_CAT_NUMBER,
+            .number = number,
+            .location = e->location,
+          };
+          return ctables_find_category_for_postcompute__ (cats, &e2);
+        }
+      else if (e->op == CTPO_CAT_SRANGE)
+        {
+          double nrange[2];
+          if (!e->srange[0].string)
+            nrange[0] = -DBL_MAX;
+          else if (!parse_category_string (e->location, e->srange[0], dict,
+                                           parse_format, &nrange[0]))
+            return NULL;
+
+          if (!e->srange[1].string)
+            nrange[1] = DBL_MAX;
+          else if (!parse_category_string (e->location, e->srange[1], dict,
+                                           parse_format, &nrange[1]))
+            return NULL;
+
+          struct ctables_pcexpr e2 = {
+            .op = CTPO_CAT_NRANGE,
+            .nrange = { nrange[0], nrange[1] },
+            .location = e->location,
+          };
+          return ctables_find_category_for_postcompute__ (cats, &e2);
+        }
+    }
+  return ctables_find_category_for_postcompute__ (cats, e);
+}
+
+static struct substring
+rtrim_value (const union value *v, const struct variable *var)
+{
+  struct substring s = ss_buffer (CHAR_CAST (char *, v->s),
+                                  var_get_width (var));
+  ss_rtrim (&s, ss_cstr (" "));
+  return s;
+}
+
+static bool
+in_string_range (const union value *v, const struct variable *var,
+                 const struct substring *srange)
+{
+  struct substring s = rtrim_value (v, var);
+  return ((!srange[0].string || ss_compare (s, srange[0]) >= 0)
+          && (!srange[1].string || ss_compare (s, srange[1]) <= 0));
+}
+
+static const struct ctables_category *
+ctables_categories_match (const struct ctables_categories *c,
+                          const union value *v, const struct variable *var)
+{
+  if (var_is_numeric (var) && v->f == SYSMIS)
+    return NULL;
+
+  const struct ctables_category *othernm = NULL;
+  for (size_t i = c->n_cats; i-- > 0; )
+    {
+      const struct ctables_category *cat = &c->cats[i];
+      switch (cat->type)
+        {
+        case CCT_NUMBER:
+          if (cat->number == v->f)
+            return cat;
+          break;
+
+        case CCT_STRING:
+          if (ss_equals (cat->string, rtrim_value (v, var)))
+            return cat;
+          break;
+
+        case CCT_NRANGE:
+          if ((cat->nrange[0] == -DBL_MAX || v->f >= cat->nrange[0])
+              && (cat->nrange[1] == DBL_MAX || v->f <= cat->nrange[1]))
+            return cat;
+          break;
+
+        case CCT_SRANGE:
+          if (in_string_range (v, var, cat->srange))
+            return cat;
+          break;
+
+        case CCT_MISSING:
+          if (var_is_value_missing (var, v))
+            return cat;
+          break;
+
+        case CCT_POSTCOMPUTE:
+          break;
+
+        case CCT_OTHERNM:
+          if (!othernm)
+            othernm = cat;
+          break;
+
+        case CCT_SUBTOTAL:
+        case CCT_TOTAL:
+          break;
+
+        case CCT_VALUE:
+        case CCT_LABEL:
+        case CCT_FUNCTION:
+          return (cat->include_missing || !var_is_value_missing (var, v) ? cat
+                  : NULL);
+
+        case CCT_EXCLUDED_MISSING:
+          break;
+        }
+    }
+
+  return var_is_value_missing (var, v) ? NULL : othernm;
+}
+
+static const struct ctables_category *
+ctables_categories_total (const struct ctables_categories *c)
+{
+  const struct ctables_category *first = &c->cats[0];
+  const struct ctables_category *last = &c->cats[c->n_cats - 1];
+  return (first->type == CCT_TOTAL ? first
+          : last->type == CCT_TOTAL ? last
+          : NULL);
+}
+
+static void
+ctables_category_format_number (double number, const struct variable *var,
+                                struct string *s)
+{
+  struct pivot_value *pv = pivot_value_new_var_value (
+    var, &(union value) { .f = number });
+  pivot_value_format (pv, NULL, s);
+  pivot_value_destroy (pv);
+}
+
+static void
+ctables_category_format_string (struct substring string,
+                                const struct variable *var, struct string *out)
+{
+  int width = var_get_width (var);
+  char *s = xmalloc (width);
+  buf_copy_rpad (s, width, string.string, string.length, ' ');
+  struct pivot_value *pv = pivot_value_new_var_value (
+    var, &(union value) { .s = CHAR_CAST (uint8_t *, s) });
+  pivot_value_format (pv, NULL, out);
+  pivot_value_destroy (pv);
+  free (s);
+}
+
+static bool
+ctables_category_format_label (const struct ctables_category *cat,
+                               const struct variable *var,
+                               struct string *s)
+{
+  switch (cat->type)
+    {
+    case CCT_NUMBER:
+      ctables_category_format_number (cat->number, var, s);
+      return true;
+
+    case CCT_STRING:
+      ctables_category_format_string (cat->string, var, s);
+      return true;
+
+    case CCT_NRANGE:
+      ctables_category_format_number (cat->nrange[0], var, s);
+      ds_put_format (s, " THRU ");
+      ctables_category_format_number (cat->nrange[1], var, s);
+      return true;
+
+    case CCT_SRANGE:
+      ctables_category_format_string (cat->srange[0], var, s);
+      ds_put_format (s, " THRU ");
+      ctables_category_format_string (cat->srange[1], var, s);
+      return true;
+
+    case CCT_MISSING:
+      ds_put_cstr (s, "MISSING");
+      return true;
+
+    case CCT_OTHERNM:
+      ds_put_cstr (s, "OTHERNM");
+      return true;
+
+    case CCT_POSTCOMPUTE:
+      ds_put_format (s, "&%s", cat->pc->name);
+      return true;
+
+    case CCT_TOTAL:
+    case CCT_SUBTOTAL:
+      ds_put_cstr (s, cat->total_label);
+      return true;
+
+    case CCT_VALUE:
+    case CCT_LABEL:
+    case CCT_FUNCTION:
+    case CCT_EXCLUDED_MISSING:
+      return false;
+    }
+
+  return false;
+}
+
+static bool
+ctables_recursive_check_postcompute (struct dictionary *dict,
+                                     const struct ctables_pcexpr *e,
+                                     struct ctables_category *pc_cat,
+                                     const struct ctables_categories *cats,
+                                     const struct msg_location *cats_location)
+{
+  switch (e->op)
+    {
+    case CTPO_CAT_NUMBER:
+    case CTPO_CAT_STRING:
+    case CTPO_CAT_NRANGE:
+    case CTPO_CAT_SRANGE:
+    case CTPO_CAT_MISSING:
+    case CTPO_CAT_OTHERNM:
+    case CTPO_CAT_SUBTOTAL:
+    case CTPO_CAT_TOTAL:
+      {
+        struct ctables_category *cat = ctables_find_category_for_postcompute (
+          dict, cats, pc_cat->parse_format, e);
+        if (!cat)
+          {
+            if (e->op == CTPO_CAT_SUBTOTAL && e->subtotal_index == 0)
+              {
+                size_t n_subtotals = 0;
+                for (size_t i = 0; i < cats->n_cats; i++)
+                  n_subtotals += cats->cats[i].type == CCT_SUBTOTAL;
+                if (n_subtotals > 1)
+                  {
+                    msg_at (SE, cats_location,
+                            ngettext ("These categories include %zu instance "
+                                      "of SUBTOTAL or HSUBTOTAL, so references "
+                                      "from computed categories must refer to "
+                                      "subtotals by position, "
+                                      "e.g. SUBTOTAL[1].",
+                                      "These categories include %zu instances "
+                                      "of SUBTOTAL or HSUBTOTAL, so references "
+                                      "from computed categories must refer to "
+                                      "subtotals by position, "
+                                      "e.g. SUBTOTAL[1].",
+                                      n_subtotals),
+                            n_subtotals);
+                    msg_at (SN, e->location,
+                            _("This is the reference that lacks a position."));
+                    return NULL;
+                  }
+              }
+
+            msg_at (SE, pc_cat->location,
+                    _("Computed category &%s references a category not included "
+                      "in the category list."),
+                    pc_cat->pc->name);
+            msg_at (SN, e->location, _("This is the missing category."));
+            if (e->op == CTPO_CAT_SUBTOTAL)
+              msg_at (SN, cats_location,
+                      _("To fix the problem, add subtotals to the "
+                        "list of categories here."));
+            else if (e->op == CTPO_CAT_TOTAL)
+              msg (SN, _("To fix the problem, add TOTAL=YES to the variable's "
+                         "CATEGORIES specification."));
+            else
+              msg_at (SN, cats_location,
+                      _("To fix the problem, add the missing category to the "
+                        "list of categories here."));
+            return false;
+          }
+        if (pc_cat->pc->hide_source_cats)
+          cat->hide = true;
+        return true;
+      }
+
+    case CTPO_CONSTANT:
+      return true;
+
+    case CTPO_ADD:
+    case CTPO_SUB:
+    case CTPO_MUL:
+    case CTPO_DIV:
+    case CTPO_POW:
+    case CTPO_NEG:
+      for (size_t i = 0; i < 2; i++)
+        if (e->subs[i] && !ctables_recursive_check_postcompute (
+              dict, e->subs[i], pc_cat, cats, cats_location))
+          return false;
+      return true;
+    }
+
+  NOT_REACHED ();
+}
+
+static struct pivot_value *
+ctables_postcompute_label (const struct ctables_categories *cats,
+                           const struct ctables_category *cat,
+                           const struct variable *var)
+{
+  struct substring in = ss_cstr (cat->pc->label);
+  struct substring target = ss_cstr (")LABEL[");
+
+  struct string out = DS_EMPTY_INITIALIZER;
+  for (;;)
+    {
+      size_t chunk = ss_find_substring (in, target);
+      if (chunk == SIZE_MAX)
+        {
+          if (ds_is_empty (&out))
+            return pivot_value_new_user_text (in.string, in.length);
+          else
+            {
+              ds_put_substring (&out, in);
+              return pivot_value_new_user_text_nocopy (ds_steal_cstr (&out));
+            }
+        }
+
+      ds_put_substring (&out, ss_head (in, chunk));
+      ss_advance (&in, chunk + target.length);
+
+      struct substring idx_s;
+      if (!ss_get_until (&in, ']', &idx_s))
+        goto error;
+      char *tail;
+      long int idx = strtol (idx_s.string, &tail, 10);
+      if (idx < 1 || idx > cats->n_cats || tail != ss_end (idx_s))
+        goto error;
+
+      struct ctables_category *cat2 = &cats->cats[idx - 1];
+      if (!ctables_category_format_label (cat2, var, &out))
+        goto error;
+    }
+
+error:
+  ds_destroy (&out);
+  return pivot_value_new_user_text (cat->pc->label, SIZE_MAX);
+}
+
+static struct pivot_value *
+ctables_category_create_value_label (const struct ctables_categories *cats,
+                                     const struct ctables_category *cat,
+                                     const struct variable *var,
+                                     const union value *value)
+{
+  return (cat->type == CCT_POSTCOMPUTE && cat->pc->label
+          ? ctables_postcompute_label (cats, cat, var)
+          : cat->type == CCT_TOTAL || cat->type == CCT_SUBTOTAL
+          ? pivot_value_new_user_text (cat->total_label, SIZE_MAX)
+          : pivot_value_new_var_value (var, value));
+}
+\f
+/* CTABLES variable nesting and stacking. */
+
+/* A nested sequence of variables, e.g. a > b > c. */
+struct ctables_nest
+  {
+    struct variable **vars;
+    size_t n;
+    size_t scale_idx;
+    size_t summary_idx;
+    size_t *areas[N_CTATS];
+    size_t n_areas[N_CTATS];
+    size_t group_head;
+
+    struct ctables_summary_spec_set specs[N_CSVS];
+  };
+
+/* A stack of nestings, e.g. nest1 + nest2 + ... + nestN. */
+struct ctables_stack
+  {
+    struct ctables_nest *nests;
+    size_t n;
+  };
+
+static void
+ctables_nest_uninit (struct ctables_nest *nest)
+{
+  free (nest->vars);
+  for (enum ctables_summary_variant sv = 0; sv < N_CSVS; sv++)
+    ctables_summary_spec_set_uninit (&nest->specs[sv]);
+  for (enum ctables_area_type at = 0; at < N_CTATS; at++)
+    free (nest->areas[at]);
+}
+
+static void
+ctables_stack_uninit (struct ctables_stack *stack)
+{
+  if (stack)
+    {
+      for (size_t i = 0; i < stack->n; i++)
+        ctables_nest_uninit (&stack->nests[i]);
+      free (stack->nests);
+    }
+}
+
+static struct ctables_stack
+nest_fts (struct ctables_stack s0, struct ctables_stack s1)
+{
+  if (!s0.n)
+    return s1;
+  else if (!s1.n)
+    return s0;
+
+  struct ctables_stack stack = { .nests = xnmalloc (s0.n, s1.n * sizeof *stack.nests) };
+  for (size_t i = 0; i < s0.n; i++)
+    for (size_t j = 0; j < s1.n; j++)
+      {
+        const struct ctables_nest *a = &s0.nests[i];
+        const struct ctables_nest *b = &s1.nests[j];
+
+        size_t allocate = a->n + b->n;
+        struct variable **vars = xnmalloc (allocate, sizeof *vars);
+        size_t n = 0;
+        for (size_t k = 0; k < a->n; k++)
+          vars[n++] = a->vars[k];
+        for (size_t k = 0; k < b->n; k++)
+          vars[n++] = b->vars[k];
+        assert (n == allocate);
+
+        const struct ctables_nest *summary_src;
+        if (!a->specs[CSV_CELL].var)
+          summary_src = b;
+        else if (!b->specs[CSV_CELL].var)
+          summary_src = a;
+        else
+          NOT_REACHED ();
+
+        struct ctables_nest *new = &stack.nests[stack.n++];
+        *new = (struct ctables_nest) {
+          .vars = vars,
+          .scale_idx = (a->scale_idx != SIZE_MAX ? a->scale_idx
+                        : b->scale_idx != SIZE_MAX ? a->n + b->scale_idx
+                        : SIZE_MAX),
+          .summary_idx = (a->summary_idx != SIZE_MAX ? a->summary_idx
+                          : b->summary_idx != SIZE_MAX ? a->n + b->summary_idx
+                          : SIZE_MAX),
+          .n = n,
+        };
+        for (enum ctables_summary_variant sv = 0; sv < N_CSVS; sv++)
+          ctables_summary_spec_set_clone (&new->specs[sv], &summary_src->specs[sv]);
+      }
+  ctables_stack_uninit (&s0);
+  ctables_stack_uninit (&s1);
+  return stack;
+}
+
+static struct ctables_stack
+stack_fts (struct ctables_stack s0, struct ctables_stack s1)
+{
+  struct ctables_stack stack = { .nests = xnmalloc (s0.n + s1.n, sizeof *stack.nests) };
+  for (size_t i = 0; i < s0.n; i++)
+    stack.nests[stack.n++] = s0.nests[i];
+  for (size_t i = 0; i < s1.n; i++)
+    {
+      stack.nests[stack.n] = s1.nests[i];
+      stack.nests[stack.n].group_head += s0.n;
+      stack.n++;
+    }
+  assert (stack.n == s0.n + s1.n);
+  free (s0.nests);
+  free (s1.nests);
+  return stack;
+}
+
+static struct ctables_stack
+var_fts (const struct ctables_axis *a)
+{
+  struct variable **vars = xmalloc (sizeof *vars);
+  *vars = a->var;
+
+  bool is_summary = a->specs[CSV_CELL].n || a->scale;
+  struct ctables_nest *nest = xmalloc (sizeof *nest);
+  *nest = (struct ctables_nest) {
+    .vars = vars,
+    .n = 1,
+    .scale_idx = a->scale ? 0 : SIZE_MAX,
+    .summary_idx = is_summary ? 0 : SIZE_MAX,
+  };
+  if (is_summary)
+    for (enum ctables_summary_variant sv = 0; sv < N_CSVS; sv++)
+      {
+        ctables_summary_spec_set_clone (&nest->specs[sv], &a->specs[sv]);
+        nest->specs[sv].var = a->var;
+        nest->specs[sv].is_scale = a->scale;
+      }
+  return (struct ctables_stack) { .nests = nest, .n = 1 };
+}
+
+static struct ctables_stack
+enumerate_fts (enum pivot_axis_type axis_type, const struct ctables_axis *a)
+{
+  if (!a)
+    return (struct ctables_stack) { .n = 0 };
+
+  switch (a->op)
+    {
+    case CTAO_VAR:
+      return var_fts (a);
+
+    case CTAO_STACK:
+      return stack_fts (enumerate_fts (axis_type, a->subs[0]),
+                        enumerate_fts (axis_type, a->subs[1]));
+
+    case CTAO_NEST:
+      /* This should consider any of the scale variables found in the result to
+         be linked to each other listwise for SMISSING=LISTWISE. */
+      return nest_fts (enumerate_fts (axis_type, a->subs[0]),
+                       enumerate_fts (axis_type, a->subs[1]));
+    }
+
+  NOT_REACHED ();
+}
+\f
+/* CTABLES summary calculation. */
+
+union ctables_summary
+  {
+    /* COUNT, VALIDN, TOTALN. */
+    double count;
+
+    /* MINIMUM, MAXIMUM, RANGE. */
+    struct
+      {
+        double min;
+        double max;
+      };
+
+    /* MEAN, SEMEAN, STDDEV, SUM, VARIANCE, *.SUM. */
+    struct moments1 *moments;
+
+    /* MEDIAN, MODE, PTILE. */
+    struct
+      {
+        struct casewriter *writer;
+        double ovalid;
+        double ovalue;
+      };
+  };
+
+static void
+ctables_summary_init (union ctables_summary *s,
+                      const struct ctables_summary_spec *ss)
+{
+  switch (ss->function)
+    {
+    case CTSF_COUNT:
+    case CTSF_areaPCT_COUNT:
+    case CTSF_areaPCT_VALIDN:
+    case CTSF_areaPCT_TOTALN:
+    case CTSF_MISSING:
+    case CTSF_TOTALN:
+    case CTSF_VALIDN:
+      s->count = 0;
+      break;
+
+    case CTSF_areaID:
+      break;
+
+    case CTSF_MAXIMUM:
+    case CTSF_MINIMUM:
+    case CTSF_RANGE:
+      s->min = s->max = SYSMIS;
+      break;
+
+    case CTSF_MEAN:
+    case CTSF_SUM:
+    case CTSF_areaPCT_SUM:
+      s->moments = moments1_create (MOMENT_MEAN);
+      break;
+
+    case CTSF_SEMEAN:
+    case CTSF_STDDEV:
+    case CTSF_VARIANCE:
+      s->moments = moments1_create (MOMENT_VARIANCE);
+      break;
+
+    case CTSF_MEDIAN:
+    case CTSF_MODE:
+    case CTSF_PTILE:
+      {
+        struct caseproto *proto = caseproto_create ();
+        proto = caseproto_add_width (proto, 0);
+        proto = caseproto_add_width (proto, 0);
+
+        struct subcase ordering;
+        subcase_init (&ordering, 0, 0, SC_ASCEND);
+        s->writer = sort_create_writer (&ordering, proto);
+        subcase_uninit (&ordering);
+        caseproto_unref (proto);
+
+        s->ovalid = 0;
+        s->ovalue = SYSMIS;
+      }
+      break;
+    }
+}
+
+static void
+ctables_summary_uninit (union ctables_summary *s,
+                        const struct ctables_summary_spec *ss)
+{
+  switch (ss->function)
+    {
+    case CTSF_COUNT:
+    case CTSF_areaPCT_COUNT:
+    case CTSF_areaPCT_VALIDN:
+    case CTSF_areaPCT_TOTALN:
+    case CTSF_MISSING:
+    case CTSF_TOTALN:
+    case CTSF_VALIDN:
+      break;
+
+    case CTSF_areaID:
+      break;
+
+    case CTSF_MAXIMUM:
+    case CTSF_MINIMUM:
+    case CTSF_RANGE:
+      break;
+
+    case CTSF_MEAN:
+    case CTSF_SEMEAN:
+    case CTSF_STDDEV:
+    case CTSF_SUM:
+    case CTSF_VARIANCE:
+    case CTSF_areaPCT_SUM:
+      moments1_destroy (s->moments);
+      break;
+
+    case CTSF_MEDIAN:
+    case CTSF_MODE:
+    case CTSF_PTILE:
+      casewriter_destroy (s->writer);
+      break;
+    }
+}
+
+static void
+ctables_summary_add (union ctables_summary *s,
+                     const struct ctables_summary_spec *ss,
+                     const union value *value,
+                     bool is_missing, bool is_included,
+                     double weight)
+{
+  /* To determine whether a case is included in a given table for a particular
+     kind of summary, consider the following charts for the variable being
+     summarized.  Only if "yes" appears is the case counted.
+
+     Categorical variables:                    VALIDN   other   TOTALN
+       Valid values in included categories       yes     yes      yes
+       Missing values in included categories     ---     yes      yes
+       Missing values in excluded categories     ---     ---      yes
+       Valid values in excluded categories       ---     ---      ---
+
+     Scale variables:                          VALIDN   other   TOTALN
+       Valid value                               yes     yes      yes
+       Missing value                             ---     yes      yes
+
+     Missing values include both user- and system-missing.  (The system-missing
+     value is always in an excluded category.)
+
+     One way to interpret the above table is that scale variables are like
+     categorical variables in which all values are in included categories.
+  */
+  switch (ss->function)
+    {
+    case CTSF_TOTALN:
+    case CTSF_areaPCT_TOTALN:
+      s->count += weight;
+      break;
+
+    case CTSF_COUNT:
+    case CTSF_areaPCT_COUNT:
+      if (is_included)
+        s->count += weight;
+      break;
+
+    case CTSF_VALIDN:
+    case CTSF_areaPCT_VALIDN:
+      if (!is_missing)
+        s->count += weight;
+      break;
+
+    case CTSF_areaID:
+      break;
+
+    case CTSF_MISSING:
+      if (is_missing)
+        s->count += weight;
+      break;
+
+    case CTSF_MAXIMUM:
+    case CTSF_MINIMUM:
+    case CTSF_RANGE:
+      if (!is_missing)
+        {
+          if (s->min == SYSMIS || value->f < s->min)
+            s->min = value->f;
+          if (s->max == SYSMIS || value->f > s->max)
+            s->max = value->f;
+        }
+      break;
+
+    case CTSF_MEAN:
+    case CTSF_SEMEAN:
+    case CTSF_STDDEV:
+    case CTSF_SUM:
+    case CTSF_VARIANCE:
+      if (!is_missing)
+        moments1_add (s->moments, value->f, weight);
+      break;
+
+    case CTSF_areaPCT_SUM:
+      if (!is_missing)
+        moments1_add (s->moments, value->f, weight);
+      break;
+
+    case CTSF_MEDIAN:
+    case CTSF_MODE:
+    case CTSF_PTILE:
+      if (!is_missing)
+        {
+          s->ovalid += weight;
+
+          struct ccase *c = case_create (casewriter_get_proto (s->writer));
+          *case_num_rw_idx (c, 0) = value->f;
+          *case_num_rw_idx (c, 1) = weight;
+          casewriter_write (s->writer, c);
+        }
+      break;
+    }
+}
+
+static double
+ctables_summary_value (struct ctables_area *areas[N_CTATS],
+                       union ctables_summary *s,
+                       const struct ctables_summary_spec *ss)
+{
+  switch (ss->function)
+    {
+    case CTSF_COUNT:
+      return s->count;
+
+    case CTSF_areaID:
+      return areas[ss->calc_area]->sequence;
+
+    case CTSF_areaPCT_COUNT:
+      {
+        const struct ctables_area *a = areas[ss->calc_area];
+        double a_count = a->count[ss->weighting];
+        return a_count ? s->count / a_count * 100 : SYSMIS;
+      }
+
+    case CTSF_areaPCT_VALIDN:
+      {
+        const struct ctables_area *a = areas[ss->calc_area];
+        double a_valid = a->valid[ss->weighting];
+        return a_valid ? s->count / a_valid * 100 : SYSMIS;
+      }
+
+    case CTSF_areaPCT_TOTALN:
+      {
+        const struct ctables_area *a = areas[ss->calc_area];
+        double a_total = a->total[ss->weighting];
+        return a_total ? s->count / a_total * 100 : SYSMIS;
+      }
+
+    case CTSF_MISSING:
+    case CTSF_TOTALN:
+    case CTSF_VALIDN:
+      return s->count;
+
+    case CTSF_MAXIMUM:
+      return s->max;
+
+    case CTSF_MINIMUM:
+      return s->min;
+
+    case CTSF_RANGE:
+      return s->max != SYSMIS && s->min != SYSMIS ? s->max - s->min : SYSMIS;
+
+    case CTSF_MEAN:
+      {
+        double mean;
+        moments1_calculate (s->moments, NULL, &mean, NULL, NULL, NULL);
+        return mean;
+      }
+
+    case CTSF_SEMEAN:
+      {
+        double weight, variance;
+        moments1_calculate (s->moments, &weight, NULL, &variance, NULL, NULL);
+        return calc_semean (variance, weight);
+      }
+
+    case CTSF_STDDEV:
+      {
+        double variance;
+        moments1_calculate (s->moments, NULL, NULL, &variance, NULL, NULL);
+        return variance != SYSMIS ? sqrt (variance) : SYSMIS;
+      }
+
+    case CTSF_SUM:
+      {
+        double weight, mean;
+        moments1_calculate (s->moments, &weight, &mean, NULL, NULL, NULL);
+        return weight != SYSMIS && mean != SYSMIS ? weight * mean : SYSMIS;
+      }
+
+    case CTSF_VARIANCE:
+      {
+        double variance;
+        moments1_calculate (s->moments, NULL, NULL, &variance, NULL, NULL);
+        return variance;
+      }
+
+    case CTSF_areaPCT_SUM:
+      {
+        double weight, mean;
+        moments1_calculate (s->moments, &weight, &mean, NULL, NULL, NULL);
+        if (weight == SYSMIS || mean == SYSMIS)
+          return SYSMIS;
+
+        const struct ctables_area *a = areas[ss->calc_area];
+        const struct ctables_sum *sum = &a->sums[ss->sum_var_idx];
+        double denom = sum->sum[ss->weighting];
+        return denom != 0 ? weight * mean / denom * 100 : SYSMIS;
+      }
+
+    case CTSF_MEDIAN:
+    case CTSF_PTILE:
+      if (s->writer)
+        {
+          struct casereader *reader = casewriter_make_reader (s->writer);
+          s->writer = NULL;
+
+          struct percentile *ptile = percentile_create (
+            ss->function == CTSF_PTILE ? ss->percentile : 0.5, s->ovalid);
+          struct order_stats *os = &ptile->parent;
+          order_stats_accumulate_idx (&os, 1, reader, 1, 0);
+          s->ovalue = percentile_calculate (ptile, PC_HAVERAGE);
+          statistic_destroy (&ptile->parent.parent);
+        }
+      return s->ovalue;
+
+    case CTSF_MODE:
+      if (s->writer)
+        {
+          struct casereader *reader = casewriter_make_reader (s->writer);
+          s->writer = NULL;
+
+          struct mode *mode = mode_create ();
+          struct order_stats *os = &mode->parent;
+          order_stats_accumulate_idx (&os, 1, reader, 1, 0);
+          s->ovalue = mode->mode;
+          statistic_destroy (&mode->parent.parent);
+        }
+      return s->ovalue;
+    }
+
+  NOT_REACHED ();
+}
+\f
+/* CTABLES occurrences. */
+
+struct ctables_occurrence
+  {
+    struct hmap_node node;
+    union value value;
+  };
+
+static void
+ctables_add_occurrence (const struct variable *var,
+                        const union value *value,
+                        struct hmap *occurrences)
+{
+  int width = var_get_width (var);
+  unsigned int hash = value_hash (value, width, 0);
+
+  struct ctables_occurrence *o;
+  HMAP_FOR_EACH_WITH_HASH (o, struct ctables_occurrence, node, hash,
+                           occurrences)
+    if (value_equal (value, &o->value, width))
+      return;
+
+  o = xmalloc (sizeof *o);
+  value_clone (&o->value, value, width);
+  hmap_insert (occurrences, &o->node, hash);
+}
+\f
+enum ctables_vlabel
+  {
+    CTVL_NONE = SETTINGS_VALUE_SHOW_DEFAULT,
+    CTVL_NAME = SETTINGS_VALUE_SHOW_VALUE,
+    CTVL_LABEL = SETTINGS_VALUE_SHOW_LABEL,
+    CTVL_BOTH = SETTINGS_VALUE_SHOW_BOTH,
+  };
+
+struct ctables_cell
+  {
+    /* In struct ctables_section's 'cells' hmap.  Indexed by all the values in
+       all the axes (except the scalar variable, if any). */
+    struct hmap_node node;
+
+    /* The areas that contain this cell. */
+    uint32_t omit_areas;
+    struct ctables_area *areas[N_CTATS];
+
+    bool hide;
+
+    bool postcompute;
+    enum ctables_summary_variant sv;
+
+    struct ctables_cell_axis
+      {
+        struct ctables_cell_value
+          {
+            const struct ctables_category *category;
+            union value value;
+          }
+        *cvs;
+        int leaf;
+      }
+    axes[PIVOT_N_AXES];
+
+    union ctables_summary *summaries;
+  };
+
+struct ctables_section
+  {
+    /* Settings. */
+    struct ctables_table *table;
+    struct ctables_nest *nests[PIVOT_N_AXES];
+
+    /* Data. */
+    struct hmap *occurrences[PIVOT_N_AXES]; /* "struct ctables_occurrence"s. */
+    struct hmap cells;            /* Contains "struct ctables_cell"s. */
+    struct hmap areas[N_CTATS];   /* Contains "struct ctables_area"s. */
+  };
+
+static void ctables_section_uninit (struct ctables_section *);
+
+struct ctables_table
+  {
+    struct ctables *ctables;
+    struct ctables_axis *axes[PIVOT_N_AXES];
+    struct ctables_stack stacks[PIVOT_N_AXES];
+    struct ctables_section *sections;
+    size_t n_sections;
+    enum pivot_axis_type summary_axis;
+    struct ctables_summary_spec_set summary_specs;
+    struct variable **sum_vars;
+    size_t n_sum_vars;
+
+    enum pivot_axis_type slabels_axis;
+    bool slabels_visible;
+
+    /* The innermost category labels for axis 'a' appear on axis label_axis[a].
+
+       Most commonly, label_axis[a] == a, and in particular we always have
+       label_axis{PIVOT_AXIS_LAYER] == PIVOT_AXIS_LAYER.
+
+       If ROWLABELS or COLLABELS is specified, then one of
+       label_axis[PIVOT_AXIS_ROW] or label_axis[PIVOT_AXIS_COLUMN] can be the
+       opposite axis or PIVOT_AXIS_LAYER.  Only one of them will differ.
+
+       If any category labels are moved, then 'clabels_example' is one of the
+       variables being moved (and it is otherwise NULL).  All of the variables
+       being moved have the same width, value labels, and categories, so this
+       example variable can be used to find those out.
+
+       The remaining members in this group are relevant only if category labels
+       are moved.
+
+       'clabels_values_map' holds a "struct ctables_value" for all the values
+       that appear in all of the variables in the moved categories.  It is
+       accumulated as the data is read.  Once the data is fully read, its
+       sorted values are put into 'clabels_values' and 'n_clabels_values'.
+    */
+    enum pivot_axis_type label_axis[PIVOT_N_AXES];
+    enum pivot_axis_type clabels_from_axis;
+    enum pivot_axis_type clabels_to_axis;
+    const struct variable *clabels_example;
+    struct hmap clabels_values_map;
+    struct ctables_value **clabels_values;
+    size_t n_clabels_values;
+
+    /* Indexed by variable dictionary index. */
+    struct ctables_categories **categories;
+    size_t n_categories;
+
+    double cilevel;
+
+    char *caption;
+    char *corner;
+    char *title;
+
+    struct ctables_chisq *chisq;
+    struct ctables_pairwise *pairwise;
+  };
+
+struct ctables_cell_sort_aux
+  {
+    const struct ctables_nest *nest;
+    enum pivot_axis_type a;
+  };
+
+static int
+ctables_cell_compare_3way (const void *a_, const void *b_, const void *aux_)
+{
+  const struct ctables_cell_sort_aux *aux = aux_;
+  struct ctables_cell *const *ap = a_;
+  struct ctables_cell *const *bp = b_;
+  const struct ctables_cell *a = *ap;
+  const struct ctables_cell *b = *bp;
+
+  const struct ctables_nest *nest = aux->nest;
+  for (size_t i = 0; i < nest->n; i++)
+    if (i != nest->scale_idx)
+      {
+        const struct variable *var = nest->vars[i];
+        const struct ctables_cell_value *a_cv = &a->axes[aux->a].cvs[i];
+        const struct ctables_cell_value *b_cv = &b->axes[aux->a].cvs[i];
+        if (a_cv->category != b_cv->category)
+          return a_cv->category > b_cv->category ? 1 : -1;
+
+        const union value *a_val = &a_cv->value;
+        const union value *b_val = &b_cv->value;
+        switch (a_cv->category->type)
+          {
+          case CCT_NUMBER:
+          case CCT_STRING:
+          case CCT_SUBTOTAL:
+          case CCT_TOTAL:
+          case CCT_POSTCOMPUTE:
+          case CCT_EXCLUDED_MISSING:
+            /* Must be equal. */
+            continue;
+
+          case CCT_NRANGE:
+          case CCT_SRANGE:
+          case CCT_MISSING:
+          case CCT_OTHERNM:
+            {
+              int cmp = value_compare_3way (a_val, b_val, var_get_width (var));
+              if (cmp)
+                return cmp;
+            }
+            break;
+
+          case CCT_VALUE:
+            {
+              int cmp = value_compare_3way (a_val, b_val, var_get_width (var));
+              if (cmp)
+                return a_cv->category->sort_ascending ? cmp : -cmp;
+            }
+            break;
+
+          case CCT_LABEL:
+            {
+              const char *a_label = var_lookup_value_label (var, a_val);
+              const char *b_label = var_lookup_value_label (var, b_val);
+              int cmp;
+              if (a_label)
+                {
+                  if (!b_label)
+                    return -1;
+                  cmp = strcmp (a_label, b_label);
+                }
+              else
+                {
+                  if (b_label)
+                    return 1;
+                  cmp = value_compare_3way (a_val, b_val, var_get_width (var));
+                }
+              if (cmp)
+                return a_cv->category->sort_ascending ? cmp : -cmp;
+            }
+            break;
+
+          case CCT_FUNCTION:
+            NOT_REACHED ();
+          }
+      }
+  return 0;
+}
+
+static int
+ctables_cell_compare_leaf_3way (const void *a_, const void *b_,
+                                const void *aux UNUSED)
+{
+  struct ctables_cell *const *ap = a_;
+  struct ctables_cell *const *bp = b_;
+  const struct ctables_cell *a = *ap;
+  const struct ctables_cell *b = *bp;
+
+  for (enum pivot_axis_type axis = 0; axis < PIVOT_N_AXES; axis++)
+    {
+      int al = a->axes[axis].leaf;
+      int bl = b->axes[axis].leaf;
+      if (al != bl)
+        return al > bl ? 1 : -1;
+    }
+  return 0;
+}
+
+static struct ctables_area *
+ctables_area_insert (struct ctables_section *s, struct ctables_cell *cell,
+                       enum ctables_area_type area)
+{
+  size_t hash = 0;
+  for (enum pivot_axis_type a = 0; a < PIVOT_N_AXES; a++)
+    {
+      const struct ctables_nest *nest = s->nests[a];
+      for (size_t i = 0; i < nest->n_areas[area]; i++)
+        {
+          size_t v_idx = nest->areas[area][i];
+          struct ctables_cell_value *cv = &cell->axes[a].cvs[v_idx];
+          hash = hash_pointer (cv->category, hash);
+          if (cv->category->type != CCT_TOTAL
+              && cv->category->type != CCT_SUBTOTAL
+              && cv->category->type != CCT_POSTCOMPUTE)
+            hash = value_hash (&cv->value,
+                               var_get_width (nest->vars[v_idx]), hash);
+        }
+    }
+
+  struct ctables_area *a;
+  HMAP_FOR_EACH_WITH_HASH (a, struct ctables_area, node, hash, &s->areas[area])
+    {
+      const struct ctables_cell *df = a->example;
+      for (enum pivot_axis_type a = 0; a < PIVOT_N_AXES; a++)
+        {
+          const struct ctables_nest *nest = s->nests[a];
+          for (size_t i = 0; i < nest->n_areas[area]; i++)
+            {
+              size_t v_idx = nest->areas[area][i];
+              struct ctables_cell_value *cv1 = &df->axes[a].cvs[v_idx];
+              struct ctables_cell_value *cv2 = &cell->axes[a].cvs[v_idx];
+              if (cv1->category != cv2->category
+                  || (cv1->category->type != CCT_TOTAL
+                      && cv1->category->type != CCT_SUBTOTAL
+                      && cv1->category->type != CCT_POSTCOMPUTE
+                      && !value_equal (&cv1->value, &cv2->value,
+                                       var_get_width (nest->vars[v_idx]))))
+                goto not_equal;
+            }
+        }
+      return a;
+
+    not_equal: ;
+    }
+
+  struct ctables_sum *sums = (s->table->n_sum_vars
+                              ? xzalloc (s->table->n_sum_vars * sizeof *sums)
+                              : NULL);
+
+  a = xmalloc (sizeof *a);
+  *a = (struct ctables_area) { .example = cell, .sums = sums };
+  hmap_insert (&s->areas[area], &a->node, hash);
+  return a;
+}
+
+static struct ctables_cell *
+ctables_cell_insert__ (struct ctables_section *s, const struct ccase *c,
+                       const struct ctables_category **cats[PIVOT_N_AXES])
+{
+  size_t hash = 0;
+  enum ctables_summary_variant sv = CSV_CELL;
+  for (enum pivot_axis_type a = 0; a < PIVOT_N_AXES; a++)
+    {
+      const struct ctables_nest *nest = s->nests[a];
+      for (size_t i = 0; i < nest->n; i++)
+        if (i != nest->scale_idx)
+          {
+            hash = hash_pointer (cats[a][i], hash);
+            if (cats[a][i]->type != CCT_TOTAL
+                && cats[a][i]->type != CCT_SUBTOTAL
+                && cats[a][i]->type != CCT_POSTCOMPUTE)
+              hash = value_hash (case_data (c, nest->vars[i]),
+                                 var_get_width (nest->vars[i]), hash);
+            else
+              sv = CSV_TOTAL;
+          }
+    }
+
+  struct ctables_cell *cell;
+  HMAP_FOR_EACH_WITH_HASH (cell, struct ctables_cell, node, hash, &s->cells)
+    {
+      for (enum pivot_axis_type a = 0; a < PIVOT_N_AXES; a++)
+        {
+          const struct ctables_nest *nest = s->nests[a];
+          for (size_t i = 0; i < nest->n; i++)
+            if (i != nest->scale_idx
+                && (cats[a][i] != cell->axes[a].cvs[i].category
+                    || (cats[a][i]->type != CCT_TOTAL
+                        && cats[a][i]->type != CCT_SUBTOTAL
+                        && cats[a][i]->type != CCT_POSTCOMPUTE
+                        && !value_equal (case_data (c, nest->vars[i]),
+                                         &cell->axes[a].cvs[i].value,
+                                         var_get_width (nest->vars[i])))))
+                goto not_equal;
+        }
+
+      return cell;
+
+    not_equal: ;
+    }
+
+  cell = xmalloc (sizeof *cell);
+  cell->hide = false;
+  cell->sv = sv;
+  cell->omit_areas = 0;
+  cell->postcompute = false;
+  for (enum pivot_axis_type a = 0; a < PIVOT_N_AXES; a++)
+    {
+      const struct ctables_nest *nest = s->nests[a];
+      cell->axes[a].cvs = (nest->n
+                           ? xnmalloc (nest->n, sizeof *cell->axes[a].cvs)
+                           : NULL);
+      for (size_t i = 0; i < nest->n; i++)
+        {
+          const struct ctables_category *cat = cats[a][i];
+          const struct variable *var = nest->vars[i];
+          const union value *value = case_data (c, var);
+          if (i != nest->scale_idx)
+            {
+              const struct ctables_category *subtotal = cat->subtotal;
+              if (cat->hide || (subtotal && subtotal->hide_subcategories))
+                cell->hide = true;
+
+              if (cat->type == CCT_TOTAL
+                  || cat->type == CCT_SUBTOTAL
+                  || cat->type == CCT_POSTCOMPUTE)
+                {
+                  switch (a)
+                    {
+                    case PIVOT_AXIS_COLUMN:
+                      cell->omit_areas |= ((1u << CTAT_TABLE) |
+                                           (1u << CTAT_LAYER) |
+                                           (1u << CTAT_LAYERCOL) |
+                                           (1u << CTAT_SUBTABLE) |
+                                           (1u << CTAT_COL));
+                      break;
+                    case PIVOT_AXIS_ROW:
+                      cell->omit_areas |= ((1u << CTAT_TABLE) |
+                                           (1u << CTAT_LAYER) |
+                                           (1u << CTAT_LAYERROW) |
+                                           (1u << CTAT_SUBTABLE) |
+                                           (1u << CTAT_ROW));
+                      break;
+                    case PIVOT_AXIS_LAYER:
+                      cell->omit_areas |= ((1u << CTAT_TABLE) |
+                                           (1u << CTAT_LAYER));
+                      break;
+                    }
+                }
+              if (cat->type == CCT_POSTCOMPUTE)
+                cell->postcompute = true;
+            }
+
+          cell->axes[a].cvs[i].category = cat;
+          value_clone (&cell->axes[a].cvs[i].value, value, var_get_width (var));
+        }
+    }
+
+  const struct ctables_nest *ss = s->nests[s->table->summary_axis];
+  const struct ctables_summary_spec_set *specs = &ss->specs[cell->sv];
+  cell->summaries = xmalloc (specs->n * sizeof *cell->summaries);
+  for (size_t i = 0; i < specs->n; i++)
+    ctables_summary_init (&cell->summaries[i], &specs->specs[i]);
+  for (enum ctables_area_type at = 0; at < N_CTATS; at++)
+    cell->areas[at] = ctables_area_insert (s, cell, at);
+  hmap_insert (&s->cells, &cell->node, hash);
+  return cell;
+}
+
+static void
+add_weight (double dst[N_CTWS], const double src[N_CTWS])
+{
+  for (enum ctables_weighting wt = 0; wt < N_CTWS; wt++)
+    dst[wt] += src[wt];
+}
+
+static void
+ctables_cell_add__ (struct ctables_section *s, const struct ccase *c,
+                    const struct ctables_category **cats[PIVOT_N_AXES],
+                    bool is_included, double weight[N_CTWS])
+{
+  struct ctables_cell *cell = ctables_cell_insert__ (s, c, cats);
+  const struct ctables_nest *ss = s->nests[s->table->summary_axis];
+
+  const struct ctables_summary_spec_set *specs = &ss->specs[cell->sv];
+  const union value *value = case_data (c, specs->var);
+  bool is_missing = var_is_value_missing (specs->var, value);
+  bool is_scale_missing
+    = is_missing || (specs->is_scale && is_listwise_missing (specs, c));
+
+  for (size_t i = 0; i < specs->n; i++)
+     ctables_summary_add (&cell->summaries[i], &specs->specs[i], value,
+                          is_scale_missing, is_included,
+                          weight[specs->specs[i].weighting]);
+  for (enum ctables_area_type at = 0; at < N_CTATS; at++)
+    if (!(cell->omit_areas && (1u << at)))
+      {
+        struct ctables_area *a = cell->areas[at];
+
+        add_weight (a->total, weight);
+        if (is_included)
+          add_weight (a->count, weight);
+        if (!is_missing)
+          {
+            add_weight (a->valid, weight);
+
+            if (!is_scale_missing)
+              for (size_t i = 0; i < s->table->n_sum_vars; i++)
+                {
+                  const struct variable *var = s->table->sum_vars[i];
+                  double addend = case_num (c, var);
+                  if (!var_is_num_missing (var, addend))
+                    for (enum ctables_weighting wt = 0; wt < N_CTWS; wt++)
+                      a->sums[i].sum[wt] += addend * weight[wt];
+                }
+          }
+      }
+}
+
+static void
+recurse_totals (struct ctables_section *s, const struct ccase *c,
+                const struct ctables_category **cats[PIVOT_N_AXES],
+                bool is_included, double weight[N_CTWS],
+                enum pivot_axis_type start_axis, size_t start_nest)
+{
+  for (enum pivot_axis_type a = start_axis; a < PIVOT_N_AXES; a++)
+    {
+      const struct ctables_nest *nest = s->nests[a];
+      for (size_t i = start_nest; i < nest->n; i++)
+        {
+          if (i == nest->scale_idx)
+            continue;
+
+          const struct variable *var = nest->vars[i];
+
+          const struct ctables_category *total = ctables_categories_total (
+            s->table->categories[var_get_dict_index (var)]);
+          if (total)
+            {
+              const struct ctables_category *save = cats[a][i];
+              cats[a][i] = total;
+              ctables_cell_add__ (s, c, cats, is_included, weight);
+              recurse_totals (s, c, cats, is_included, weight, a, i + 1);
+              cats[a][i] = save;
+            }
+        }
+      start_nest = 0;
+    }
+}
+
+static void
+recurse_subtotals (struct ctables_section *s, const struct ccase *c,
+                   const struct ctables_category **cats[PIVOT_N_AXES],
+                   bool is_included, double weight[N_CTWS],
+                   enum pivot_axis_type start_axis, size_t start_nest)
+{
+  for (enum pivot_axis_type a = start_axis; a < PIVOT_N_AXES; a++)
+    {
+      const struct ctables_nest *nest = s->nests[a];
+      for (size_t i = start_nest; i < nest->n; i++)
+        {
+          if (i == nest->scale_idx)
+            continue;
+
+          const struct ctables_category *save = cats[a][i];
+          if (save->subtotal)
+            {
+              cats[a][i] = save->subtotal;
+              ctables_cell_add__ (s, c, cats, is_included, weight);
+              recurse_subtotals (s, c, cats, is_included, weight, a, i + 1);
+              cats[a][i] = save;
+            }
+        }
+      start_nest = 0;
+    }
+}
+
+static void
+ctables_cell_insert (struct ctables_section *s, const struct ccase *c,
+                     double weight[N_CTWS])
+{
+  const struct ctables_category *layer_cats[s->nests[PIVOT_AXIS_LAYER]->n];
+  const struct ctables_category *row_cats[s->nests[PIVOT_AXIS_ROW]->n];
+  const struct ctables_category *column_cats[s->nests[PIVOT_AXIS_COLUMN]->n];
+  const struct ctables_category **cats[PIVOT_N_AXES] =
+    {
+      [PIVOT_AXIS_LAYER] = layer_cats,
+      [PIVOT_AXIS_ROW] = row_cats,
+      [PIVOT_AXIS_COLUMN] = column_cats,
+    };
+
+  bool is_included = true;
+
+  for (enum pivot_axis_type a = 0; a < PIVOT_N_AXES; a++)
+    {
+      const struct ctables_nest *nest = s->nests[a];
+      for (size_t i = 0; i < nest->n; i++)
+        if (i != nest->scale_idx)
+          {
+            const struct variable *var = nest->vars[i];
+            const union value *value = case_data (c, var);
+
+            cats[a][i] = ctables_categories_match (
+              s->table->categories[var_get_dict_index (var)], value, var);
+            if (!cats[a][i])
+              {
+                if (i != nest->summary_idx)
+                  return;
+
+                if (!var_is_value_missing (var, value))
+                  return;
+
+                static const struct ctables_category cct_excluded_missing = {
+                  .type = CCT_EXCLUDED_MISSING,
+                  .hide = true,
+                };
+                cats[a][i] = &cct_excluded_missing;
+                is_included = false;
+              }
+        }
+    }
+
+  if (is_included)
+    for (enum pivot_axis_type a = 0; a < PIVOT_N_AXES; a++)
+      {
+        const struct ctables_nest *nest = s->nests[a];
+        for (size_t i = 0; i < nest->n; i++)
+          if (i != nest->scale_idx)
+            {
+              const struct variable *var = nest->vars[i];
+              const union value *value = case_data (c, var);
+              ctables_add_occurrence (var, value, &s->occurrences[a][i]);
+            }
+      }
+
+  ctables_cell_add__ (s, c, cats, is_included, weight);
+  recurse_totals (s, c, cats, is_included, weight, 0, 0);
+  recurse_subtotals (s, c, cats, is_included, weight, 0, 0);
+}
+\f
+struct ctables_value
+  {
+    struct hmap_node node;
+    union value value;
+    int leaf;
+  };
+
+static struct ctables_value *
+ctables_value_find__ (struct ctables_table *t, const union value *value,
+                      int width, unsigned int hash)
+{
+  struct ctables_value *clv;
+  HMAP_FOR_EACH_WITH_HASH (clv, struct ctables_value, node,
+                           hash, &t->clabels_values_map)
+    if (value_equal (value, &clv->value, width))
+      return clv;
+  return NULL;
+}
+
+static void
+ctables_value_insert (struct ctables_table *t, const union value *value,
+                      int width)
+{
+  unsigned int hash = value_hash (value, width, 0);
+  struct ctables_value *clv = ctables_value_find__ (t, value, width, hash);
+  if (!clv)
+    {
+      clv = xmalloc (sizeof *clv);
+      value_clone (&clv->value, value, width);
+      hmap_insert (&t->clabels_values_map, &clv->node, hash);
+    }
+}
+
+static struct ctables_value *
+ctables_value_find (struct ctables_table *t,
+                    const union value *value, int width)
+{
+  return ctables_value_find__ (t, value, width,
+                               value_hash (value, width, 0));
+}
+
+static int
+compare_ctables_values_3way (const void *a_, const void *b_, const void *width_)
+{
+  const struct ctables_value *const *ap = a_;
+  const struct ctables_value *const *bp = b_;
+  const struct ctables_value *a = *ap;
+  const struct ctables_value *b = *bp;
+  const int *width = width_;
+  return value_compare_3way (&a->value, &b->value, *width);
+}
+
+static void
+ctables_sort_clabels_values (struct ctables_table *t)
+{
+  const struct variable *v0 = t->clabels_example;
+  int width = var_get_width (v0);
+
+  struct ctables_categories *c0 = t->categories[var_get_dict_index (v0)];
+  if (c0->show_empty)
+    {
+      const struct val_labs *val_labs = var_get_value_labels (v0);
+      for (const struct val_lab *vl = val_labs_first (val_labs); vl;
+           vl = val_labs_next (val_labs, vl))
+        if (ctables_categories_match (c0, &vl->value, v0))
+          ctables_value_insert (t, &vl->value, width);
+    }
+
+  size_t n = hmap_count (&t->clabels_values_map);
+  t->clabels_values = xnmalloc (n, sizeof *t->clabels_values);
+
+  struct ctables_value *clv;
+  size_t i = 0;
+  HMAP_FOR_EACH (clv, struct ctables_value, node, &t->clabels_values_map)
+    t->clabels_values[i++] = clv;
+  t->n_clabels_values = n;
+  assert (i == n);
+
+  sort (t->clabels_values, n, sizeof *t->clabels_values,
+        compare_ctables_values_3way, &width);
+
+  for (size_t i = 0; i < n; i++)
+    t->clabels_values[i]->leaf = i;
+}
+\f
+struct ctables
+  {
+    const struct dictionary *dict;
+    struct pivot_table_look *look;
+
+    /* For CTEF_* formats. */
+    struct fmt_settings ctables_formats;
+
+    /* If this is NULL, zeros are displayed using the normal print format.
+       Otherwise, this string is displayed. */
+    char *zero;
+
+    /* If this is NULL, missing values are displayed using the normal print
+       format.  Otherwise, this string is displayed. */
+    char *missing;
+
+    /* Indexed by variable dictionary index. */
+    enum ctables_vlabel *vlabels;
+
+    struct hmap postcomputes;   /* Contains "struct ctables_postcompute"s. */
+
+    bool mrsets_count_duplicates; /* MRSETS. */
+    bool smissing_listwise;       /* SMISSING. */
+    struct variable *e_weight;    /* WEIGHT. */
+    int hide_threshold;           /* HIDESMALLCOUNTS. */
+
+    struct ctables_table **tables;
+    size_t n_tables;
+  };
+\f
+static double
+ctpo_add (double a, double b)
+{
+  return a + b;
+}
+
+static double
+ctpo_sub (double a, double b)
+{
+  return a - b;
+}
+
+static double
+ctpo_mul (double a, double b)
+{
+  return a * b;
+}
+
+static double
+ctpo_div (double a, double b)
+{
+  return b ? a / b : SYSMIS;
+}
+
+static double
+ctpo_pow (double a, double b)
+{
+  int save_errno = errno;
+  errno = 0;
+  double result = pow (a, b);
+  if (errno)
+    result = SYSMIS;
+  errno = save_errno;
+  return result;
+}
+
+static double
+ctpo_neg (double a, double b UNUSED)
+{
+  return -a;
+}
+
+struct ctables_pcexpr_evaluate_ctx
+  {
+    const struct ctables_cell *cell;
+    const struct ctables_section *section;
+    const struct ctables_categories *cats;
+    enum pivot_axis_type pc_a;
+    size_t pc_a_idx;
+    size_t summary_idx;
+    enum fmt_type parse_format;
+  };
+
+static double ctables_pcexpr_evaluate (
+  const struct ctables_pcexpr_evaluate_ctx *, const struct ctables_pcexpr *);
+
+static double
+ctables_pcexpr_evaluate_nonterminal (
+  const struct ctables_pcexpr_evaluate_ctx *ctx,
+  const struct ctables_pcexpr *e, size_t n_args,
+  double evaluate (double, double))
+{
+  double args[2] = { 0, 0 };
+  for (size_t i = 0; i < n_args; i++)
+    {
+      args[i] = ctables_pcexpr_evaluate (ctx, e->subs[i]);
+      if (!isfinite (args[i]) || args[i] == SYSMIS)
+        return SYSMIS;
+    }
+  return evaluate (args[0], args[1]);
+}
+
+static double
+ctables_pcexpr_evaluate_category (const struct ctables_pcexpr_evaluate_ctx *ctx,
+                                  const struct ctables_cell_value *pc_cv)
+{
+  const struct ctables_section *s = ctx->section;
+
+  size_t hash = 0;
+  for (enum pivot_axis_type a = 0; a < PIVOT_N_AXES; a++)
+    {
+      const struct ctables_nest *nest = s->nests[a];
+      for (size_t i = 0; i < nest->n; i++)
+        if (i != nest->scale_idx)
+          {
+            const struct ctables_cell_value *cv
+              = (a == ctx->pc_a && i == ctx->pc_a_idx ? pc_cv
+                 : &ctx->cell->axes[a].cvs[i]);
+            hash = hash_pointer (cv->category, hash);
+            if (cv->category->type != CCT_TOTAL
+                && cv->category->type != CCT_SUBTOTAL
+                && cv->category->type != CCT_POSTCOMPUTE)
+              hash = value_hash (&cv->value,
+                                 var_get_width (nest->vars[i]), hash);
+          }
+    }
+
+  struct ctables_cell *tc;
+  HMAP_FOR_EACH_WITH_HASH (tc, struct ctables_cell, node, hash, &s->cells)
+    {
+      for (enum pivot_axis_type a = 0; a < PIVOT_N_AXES; a++)
+        {
+          const struct ctables_nest *nest = s->nests[a];
+          for (size_t i = 0; i < nest->n; i++)
+            if (i != nest->scale_idx)
+              {
+                const struct ctables_cell_value *p_cv
+                  = (a == ctx->pc_a && i == ctx->pc_a_idx ? pc_cv
+                     : &ctx->cell->axes[a].cvs[i]);
+                const struct ctables_cell_value *t_cv = &tc->axes[a].cvs[i];
+                if (p_cv->category != t_cv->category
+                    || (p_cv->category->type != CCT_TOTAL
+                        && p_cv->category->type != CCT_SUBTOTAL
+                        && p_cv->category->type != CCT_POSTCOMPUTE
+                        && !value_equal (&p_cv->value,
+                                         &t_cv->value,
+                                         var_get_width (nest->vars[i]))))
+                  goto not_equal;
+              }
+        }
+
+      goto found;
+
+    not_equal: ;
+    }
+  return 0;
+
+found: ;
+  const struct ctables_table *t = s->table;
+  const struct ctables_nest *specs_nest = s->nests[t->summary_axis];
+  const struct ctables_summary_spec_set *specs = &specs_nest->specs[tc->sv];
+  return ctables_summary_value (tc->areas, &tc->summaries[ctx->summary_idx],
+                                &specs->specs[ctx->summary_idx]);
+}
+
+static double
+ctables_pcexpr_evaluate (const struct ctables_pcexpr_evaluate_ctx *ctx,
+                         const struct ctables_pcexpr *e)
+{
+  switch (e->op)
+    {
+    case CTPO_CONSTANT:
+      return e->number;
+
+    case CTPO_CAT_NRANGE:
+    case CTPO_CAT_SRANGE:
+    case CTPO_CAT_MISSING:
+    case CTPO_CAT_OTHERNM:
+      {
+        struct ctables_cell_value cv = {
+          .category = ctables_find_category_for_postcompute (ctx->section->table->ctables->dict, ctx->cats, ctx->parse_format, e)
+        };
+        assert (cv.category != NULL);
+
+        struct hmap *occurrences = &ctx->section->occurrences[ctx->pc_a][ctx->pc_a_idx];
+        const struct ctables_occurrence *o;
+
+        double sum = 0.0;
+        const struct variable *var = ctx->section->nests[ctx->pc_a]->vars[ctx->pc_a_idx];
+        HMAP_FOR_EACH (o, struct ctables_occurrence, node, occurrences)
+          if (ctables_categories_match (ctx->cats, &o->value, var) == cv.category)
+            {
+              cv.value = o->value;
+              sum += ctables_pcexpr_evaluate_category (ctx, &cv);
+            }
+        return sum;
+      }
+
+    case CTPO_CAT_NUMBER:
+    case CTPO_CAT_SUBTOTAL:
+    case CTPO_CAT_TOTAL:
+      {
+        struct ctables_cell_value cv = {
+          .category = ctables_find_category_for_postcompute (ctx->section->table->ctables->dict, ctx->cats, ctx->parse_format, e),
+          .value = { .f = e->number },
+        };
+        assert (cv.category != NULL);
+        return ctables_pcexpr_evaluate_category (ctx, &cv);
+      }
+
+    case CTPO_CAT_STRING:
+      {
+        int width = var_get_width (ctx->section->nests[ctx->pc_a]->vars[ctx->pc_a_idx]);
+        char *s = NULL;
+        if (width > e->string.length)
+          {
+            s = xmalloc (width);
+            buf_copy_rpad (s, width, e->string.string, e->string.length, ' ');
+          }
+
+        const struct ctables_category *category
+          = ctables_find_category_for_postcompute (
+            ctx->section->table->ctables->dict,
+            ctx->cats, ctx->parse_format, e);
+        assert (category != NULL);
+
+        struct ctables_cell_value cv = { .category = category };
+        if (category->type == CCT_NUMBER)
+          cv.value.f = category->number;
+        else if (category->type == CCT_STRING)
+          cv.value.s = CHAR_CAST (uint8_t *, s ? s : e->string.string);
+        else
+          NOT_REACHED ();
+
+        double retval = ctables_pcexpr_evaluate_category (ctx, &cv);
+        free (s);
+        return retval;
+      }
+
+    case CTPO_ADD:
+      return ctables_pcexpr_evaluate_nonterminal (ctx, e, 2, ctpo_add);
+
+    case CTPO_SUB:
+      return ctables_pcexpr_evaluate_nonterminal (ctx, e, 2, ctpo_sub);
+
+    case CTPO_MUL:
+      return ctables_pcexpr_evaluate_nonterminal (ctx, e, 2, ctpo_mul);
+
+    case CTPO_DIV:
+      return ctables_pcexpr_evaluate_nonterminal (ctx, e, 2, ctpo_div);
+
+    case CTPO_POW:
+      return ctables_pcexpr_evaluate_nonterminal (ctx, e, 2, ctpo_pow);
+
+    case CTPO_NEG:
+      return ctables_pcexpr_evaluate_nonterminal (ctx, e, 1, ctpo_neg);
+    }
+
+  NOT_REACHED ();
+}
+
+static const struct ctables_category *
+ctables_cell_postcompute (const struct ctables_section *s,
+                          const struct ctables_cell *cell,
+                          enum pivot_axis_type *pc_a_p,
+                          size_t *pc_a_idx_p)
+{
+  assert (cell->postcompute);
+  const struct ctables_category *pc_cat = NULL;
+  for (enum pivot_axis_type pc_a = 0; pc_a < PIVOT_N_AXES; pc_a++)
+    for (size_t pc_a_idx = 0; pc_a_idx < s->nests[pc_a]->n; pc_a_idx++)
+      {
+        const struct ctables_cell_value *cv = &cell->axes[pc_a].cvs[pc_a_idx];
+        if (cv->category->type == CCT_POSTCOMPUTE)
+          {
+            if (pc_cat)
+              {
+                /* Multiple postcomputes cross each other.  The value is
+                   undefined. */
+                return NULL;
+              }
+
+            pc_cat = cv->category;
+            if (pc_a_p)
+              *pc_a_p = pc_a;
+            if (pc_a_idx_p)
+              *pc_a_idx_p = pc_a_idx;
+          }
+      }
+
+  assert (pc_cat != NULL);
+  return pc_cat;
+}
+
+static double
+ctables_cell_calculate_postcompute (const struct ctables_section *s,
+                                    const struct ctables_cell *cell,
+                                    const struct ctables_summary_spec *ss,
+                                    struct fmt_spec *format,
+                                    bool *is_ctables_format,
+                                    size_t summary_idx)
+{
+  enum pivot_axis_type pc_a = 0;
+  size_t pc_a_idx = 0;
+  const struct ctables_category *pc_cat = ctables_cell_postcompute (
+    s, cell, &pc_a, &pc_a_idx);
+  if (!pc_cat)
+    return SYSMIS;
+
+  const struct ctables_postcompute *pc = pc_cat->pc;
+  if (pc->specs)
+    {
+      for (size_t i = 0; i < pc->specs->n; i++)
+        {
+          const struct ctables_summary_spec *ss2 = &pc->specs->specs[i];
+          if (ss->function == ss2->function
+              && ss->weighting == ss2->weighting
+              && ss->calc_area == ss2->calc_area
+              && ss->percentile == ss2->percentile)
+            {
+              *format = ss2->format;
+              *is_ctables_format = ss2->is_ctables_format;
+              break;
+            }
+        }
+    }
+
+  const struct variable *var = s->nests[pc_a]->vars[pc_a_idx];
+  const struct ctables_categories *cats = s->table->categories[
+    var_get_dict_index (var)];
+  struct ctables_pcexpr_evaluate_ctx ctx = {
+    .cell = cell,
+    .section = s,
+    .cats = cats,
+    .pc_a = pc_a,
+    .pc_a_idx = pc_a_idx,
+    .summary_idx = summary_idx,
+    .parse_format = pc_cat->parse_format,
+  };
+  return ctables_pcexpr_evaluate (&ctx, pc->expr);
+}
+\f
+/* Chi-square test (SIGTEST). */
+struct ctables_chisq
+  {
+    double alpha;
+    bool include_mrsets;
+    bool all_visible;
+  };
+
+/* Pairwise comparison test (COMPARETEST). */
+struct ctables_pairwise
+  {
+    enum { PROP, MEAN } type;
+    double alpha[2];
+    bool include_mrsets;
+    bool meansvariance_allcats;
+    bool all_visible;
+    enum { BONFERRONI = 1, BH } adjust;
+    bool merge;
+    bool apa_style;
+    bool show_sig;
+  };
+
+
+
+static bool
+parse_col_width (struct lexer *lexer, const char *name, double *width)
+{
+  lex_match (lexer, T_EQUALS);
+  if (lex_match_id (lexer, "DEFAULT"))
+    *width = SYSMIS;
+  else if (lex_force_num_range_closed (lexer, name, 0, DBL_MAX))
+    {
+      *width = lex_number (lexer);
+      lex_get (lexer);
+    }
+  else
+    return false;
+
+  return true;
+}
+
+static bool
+parse_bool (struct lexer *lexer, bool *b)
+{
+  if (lex_match_id (lexer, "NO"))
+    *b = false;
+  else if (lex_match_id (lexer, "YES"))
+    *b = true;
+  else
+    {
+      lex_error_expecting (lexer, "YES", "NO");
+      return false;
+    }
+  return true;
+}
+
+static void
+ctables_chisq_destroy (struct ctables_chisq *chisq)
+{
+  free (chisq);
+}
+
+static void
+ctables_pairwise_destroy (struct ctables_pairwise *pairwise)
+{
+  free (pairwise);
+}
+
+static void
+ctables_table_destroy (struct ctables_table *t)
+{
+  if (!t)
+    return;
+
+  for (size_t i = 0; i < t->n_sections; i++)
+    ctables_section_uninit (&t->sections[i]);
+  free (t->sections);
+
+  for (size_t i = 0; i < t->n_categories; i++)
+    ctables_categories_unref (t->categories[i]);
+  free (t->categories);
+
+  for (enum pivot_axis_type a = 0; a < PIVOT_N_AXES; a++)
+    {
+      ctables_axis_destroy (t->axes[a]);
+      ctables_stack_uninit (&t->stacks[a]);
+    }
+  free (t->summary_specs.specs);
+
+  struct ctables_value *ctv, *next_ctv;
+  HMAP_FOR_EACH_SAFE (ctv, next_ctv, struct ctables_value, node,
+                      &t->clabels_values_map)
+    {
+      value_destroy (&ctv->value, var_get_width (t->clabels_example));
+      hmap_delete (&t->clabels_values_map, &ctv->node);
+      free (ctv);
+    }
+  hmap_destroy (&t->clabels_values_map);
+  free (t->clabels_values);
+
+  free (t->sum_vars);
+  free (t->caption);
+  free (t->corner);
+  free (t->title);
+  ctables_chisq_destroy (t->chisq);
+  ctables_pairwise_destroy (t->pairwise);
+  free (t);
+}
+
+static void
+ctables_destroy (struct ctables *ct)
+{
+  if (!ct)
+    return;
+
+  struct ctables_postcompute *pc, *next_pc;
+  HMAP_FOR_EACH_SAFE (pc, next_pc, struct ctables_postcompute, hmap_node,
+                      &ct->postcomputes)
+    {
+      free (pc->name);
+      msg_location_destroy (pc->location);
+      ctables_pcexpr_destroy (pc->expr);
+      free (pc->label);
+      if (pc->specs)
+        {
+          ctables_summary_spec_set_uninit (pc->specs);
+          free (pc->specs);
+        }
+      hmap_delete (&ct->postcomputes, &pc->hmap_node);
+      free (pc);
+    }
+  hmap_destroy (&ct->postcomputes);
+
+  fmt_settings_uninit (&ct->ctables_formats);
+  pivot_table_look_unref (ct->look);
+  free (ct->zero);
+  free (ct->missing);
+  free (ct->vlabels);
+  for (size_t i = 0; i < ct->n_tables; i++)
+    ctables_table_destroy (ct->tables[i]);
+  free (ct->tables);
+  free (ct);
+}
+
+static bool
+all_strings (struct variable **vars, size_t n_vars,
+             const struct ctables_category *cat)
+{
+  for (size_t j = 0; j < n_vars; j++)
+    if (var_is_numeric (vars[j]))
+      {
+        msg_at (SE, cat->location,
+                _("This category specification may be applied only to string "
+                  "variables, but this subcommand tries to apply it to "
+                  "numeric variable %s."),
+                var_get_name (vars[j]));
+        return false;
+      }
+  return true;
+}
+
+static bool
+ctables_table_parse_categories (struct lexer *lexer, struct dictionary *dict,
+                                struct ctables *ct, struct ctables_table *t)
+{
+  if (!lex_force_match_id (lexer, "VARIABLES"))
+    return false;
+  lex_match (lexer, T_EQUALS);
+
+  struct variable **vars;
+  size_t n_vars;
+  if (!parse_variables (lexer, dict, &vars, &n_vars, PV_NO_SCRATCH))
+    return false;
+
+  const struct fmt_spec *common_format = var_get_print_format (vars[0]);
+  for (size_t i = 1; i < n_vars; i++)
+    {
+      const struct fmt_spec *f = var_get_print_format (vars[i]);
+      if (f->type != common_format->type)
+        {
+          common_format = NULL;
+          break;
+        }
+    }
+  bool parse_strings
+    = (common_format
+       && (fmt_get_category (common_format->type)
+           & (FMT_CAT_DATE | FMT_CAT_TIME | FMT_CAT_DATE_COMPONENT)));
+
+  struct ctables_categories *c = xmalloc (sizeof *c);
+  *c = (struct ctables_categories) { .n_refs = n_vars, .show_empty = true };
+  for (size_t i = 0; i < n_vars; i++)
+    {
+      struct ctables_categories **cp
+        = &t->categories[var_get_dict_index (vars[i])];
+      ctables_categories_unref (*cp);
+      *cp = c;
+    }
+
+  size_t allocated_cats = 0;
+  int cats_start_ofs = -1;
+  int cats_end_ofs = -1;
+  if (lex_match (lexer, T_LBRACK))
+    {
+      cats_start_ofs = lex_ofs (lexer);
+      do
+        {
+          if (c->n_cats >= allocated_cats)
+            c->cats = x2nrealloc (c->cats, &allocated_cats, sizeof *c->cats);
+
+          int start_ofs = lex_ofs (lexer);
+          struct ctables_category *cat = &c->cats[c->n_cats];
+          if (!ctables_table_parse_explicit_category (lexer, dict, ct, cat))
+            goto error;
+          cat->location = lex_ofs_location (lexer, start_ofs, lex_ofs (lexer) - 1);
+          c->n_cats++;
+
+          lex_match (lexer, T_COMMA);
+        }
+      while (!lex_match (lexer, T_RBRACK));
+      cats_end_ofs = lex_ofs (lexer) - 1;
+    }
+
+  struct ctables_category cat = {
+    .type = CCT_VALUE,
+    .include_missing = false,
+    .sort_ascending = true,
+  };
+  bool show_totals = false;
+  char *total_label = NULL;
+  bool totals_before = false;
+  while (lex_token (lexer) != T_SLASH && lex_token (lexer) != T_ENDCMD)
+    {
+      if (!c->n_cats && lex_match_id (lexer, "ORDER"))
+        {
+          lex_match (lexer, T_EQUALS);
+          if (lex_match_id (lexer, "A"))
+            cat.sort_ascending = true;
+          else if (lex_match_id (lexer, "D"))
+            cat.sort_ascending = false;
+          else
+            {
+              lex_error_expecting (lexer, "A", "D");
+              goto error;
+            }
+        }
+      else if (!c->n_cats && lex_match_id (lexer, "KEY"))
+        {
+          int start_ofs = lex_ofs (lexer) - 1;
+          lex_match (lexer, T_EQUALS);
+          if (lex_match_id (lexer, "VALUE"))
+            cat.type = CCT_VALUE;
+          else if (lex_match_id (lexer, "LABEL"))
+            cat.type = CCT_LABEL;
+          else
+            {
+              cat.type = CCT_FUNCTION;
+              if (!parse_ctables_summary_function (lexer, &cat.sort_function,
+                                                   &cat.weighting, &cat.area))
+                goto error;
+
+              if (lex_match (lexer, T_LPAREN))
+                {
+                  cat.sort_var = parse_variable (lexer, dict);
+                  if (!cat.sort_var)
+                    goto error;
+
+                  if (cat.sort_function == CTSF_PTILE)
+                    {
+                      lex_match (lexer, T_COMMA);
+                      if (!lex_force_num_range_closed (lexer, "PTILE", 0, 100))
+                        goto error;
+                      cat.percentile = lex_number (lexer);
+                      lex_get (lexer);
+                    }
+
+                  if (!lex_force_match (lexer, T_RPAREN))
+                    goto error;
+                }
+              else if (ctables_function_availability (cat.sort_function)
+                       == CTFA_SCALE)
+                {
+                  bool UNUSED b = lex_force_match (lexer, T_LPAREN);
+                  goto error;
+                }
+
+              lex_ofs_error (lexer, start_ofs, lex_ofs (lexer) - 1,
+                              _("Data-dependent sorting is not implemented."));
+              goto error;
+            }
+        }
+      else if (!c->n_cats && lex_match_id (lexer, "MISSING"))
+        {
+          lex_match (lexer, T_EQUALS);
+          if (lex_match_id (lexer, "INCLUDE"))
+            cat.include_missing = true;
+          else if (lex_match_id (lexer, "EXCLUDE"))
+            cat.include_missing = false;
+          else
+            {
+              lex_error_expecting (lexer, "INCLUDE", "EXCLUDE");
+              goto error;
+            }
+        }
+      else if (lex_match_id (lexer, "TOTAL"))
+        {
+          lex_match (lexer, T_EQUALS);
+          if (!parse_bool (lexer, &show_totals))
+            goto error;
+        }
+      else if (lex_match_id (lexer, "LABEL"))
+        {
+          lex_match (lexer, T_EQUALS);
+          if (!lex_force_string (lexer))
+            goto error;
+          free (total_label);
+          total_label = ss_xstrdup (lex_tokss (lexer));
+          lex_get (lexer);
+        }
+      else if (lex_match_id (lexer, "POSITION"))
+        {
+          lex_match (lexer, T_EQUALS);
+          if (lex_match_id (lexer, "BEFORE"))
+            totals_before = true;
+          else if (lex_match_id (lexer, "AFTER"))
+            totals_before = false;
+          else
+            {
+              lex_error_expecting (lexer, "BEFORE", "AFTER");
+              goto error;
+            }
+        }
+      else if (lex_match_id (lexer, "EMPTY"))
+        {
+          lex_match (lexer, T_EQUALS);
+          if (lex_match_id (lexer, "INCLUDE"))
+            c->show_empty = true;
+          else if (lex_match_id (lexer, "EXCLUDE"))
+            c->show_empty = false;
+          else
+            {
+              lex_error_expecting (lexer, "INCLUDE", "EXCLUDE");
+              goto error;
+            }
+        }
+      else
+        {
+          if (!c->n_cats)
+            lex_error_expecting (lexer, "ORDER", "KEY", "MISSING",
+                                 "TOTAL", "LABEL", "POSITION", "EMPTY");
+          else
+            lex_error_expecting (lexer, "TOTAL", "LABEL", "POSITION", "EMPTY");
+          goto error;
+        }
+    }
+
+  if (!c->n_cats)
+    {
+      if (c->n_cats >= allocated_cats)
+        c->cats = x2nrealloc (c->cats, &allocated_cats, sizeof *c->cats);
+      c->cats[c->n_cats++] = cat;
+    }
+
+  if (show_totals)
+    {
+      if (c->n_cats >= allocated_cats)
+        c->cats = x2nrealloc (c->cats, &allocated_cats, sizeof *c->cats);
+
+      struct ctables_category *totals;
+      if (totals_before)
+        {
+          insert_element (c->cats, c->n_cats, sizeof *c->cats, 0);
+          totals = &c->cats[0];
+        }
+      else
+        totals = &c->cats[c->n_cats];
+      c->n_cats++;
+
+      *totals = (struct ctables_category) {
+        .type = CCT_TOTAL,
+        .total_label = total_label ? total_label : xstrdup (_("Total")),
+      };
+    }
+
+  struct ctables_category *subtotal = NULL;
+  for (size_t i = totals_before ? 0 : c->n_cats;
+       totals_before ? i < c->n_cats : i-- > 0;
+       totals_before ? i++ : 0)
+    {
+      struct ctables_category *cat = &c->cats[i];
+      switch (cat->type)
+        {
+        case CCT_NUMBER:
+        case CCT_STRING:
+        case CCT_NRANGE:
+        case CCT_SRANGE:
+        case CCT_MISSING:
+        case CCT_OTHERNM:
+          cat->subtotal = subtotal;
+          break;
+
+        case CCT_POSTCOMPUTE:
+          break;
+
+        case CCT_SUBTOTAL:
+          subtotal = cat;
+          break;
+
+        case CCT_TOTAL:
+        case CCT_VALUE:
+        case CCT_LABEL:
+        case CCT_FUNCTION:
+        case CCT_EXCLUDED_MISSING:
+          break;
+        }
+    }
+
+  if (cats_start_ofs != -1)
+    {
+      for (size_t i = 0; i < c->n_cats; i++)
+        {
+          struct ctables_category *cat = &c->cats[i];
+          switch (cat->type)
+            {
+            case CCT_POSTCOMPUTE:
+              cat->parse_format = parse_strings ? common_format->type : FMT_F;
+              struct msg_location *cats_location
+                = lex_ofs_location (lexer, cats_start_ofs, cats_end_ofs);
+              bool ok = ctables_recursive_check_postcompute (
+                dict, cat->pc->expr, cat, c, cats_location);
+              msg_location_destroy (cats_location);
+              if (!ok)
+                goto error;
+              break;
+
+            case CCT_NUMBER:
+            case CCT_NRANGE:
+              for (size_t j = 0; j < n_vars; j++)
+                if (var_is_alpha (vars[j]))
+                  {
+                    msg_at (SE, cat->location,
+                            _("This category specification may be applied "
+                              "only to numeric variables, but this "
+                              "subcommand tries to apply it to string "
+                              "variable %s."),
+                            var_get_name (vars[j]));
+                    goto error;
+                  }
+              break;
+
+            case CCT_STRING:
+              if (parse_strings)
+                {
+                  double n;
+                  if (!parse_category_string (cat->location, cat->string, dict,
+                                              common_format->type, &n))
+                    goto error;
+
+                  ss_dealloc (&cat->string);
+
+                  cat->type = CCT_NUMBER;
+                  cat->number = n;
+                }
+              else if (!all_strings (vars, n_vars, cat))
+                goto error;
+              break;
+
+            case CCT_SRANGE:
+              if (parse_strings)
+                {
+                  double n[2];
+
+                  if (!cat->srange[0].string)
+                    n[0] = -DBL_MAX;
+                  else if (!parse_category_string (cat->location,
+                                                   cat->srange[0], dict,
+                                                   common_format->type, &n[0]))
+                    goto error;
+
+                  if (!cat->srange[1].string)
+                    n[1] = DBL_MAX;
+                  else if (!parse_category_string (cat->location,
+                                                   cat->srange[1], dict,
+                                                   common_format->type, &n[1]))
+                    goto error;
+
+                  ss_dealloc (&cat->srange[0]);
+                  ss_dealloc (&cat->srange[1]);
+
+                  cat->type = CCT_NRANGE;
+                  cat->nrange[0] = n[0];
+                  cat->nrange[1] = n[1];
+                }
+              else if (!all_strings (vars, n_vars, cat))
+                goto error;
+              break;
+
+            case CCT_MISSING:
+            case CCT_OTHERNM:
+            case CCT_SUBTOTAL:
+            case CCT_TOTAL:
+            case CCT_VALUE:
+            case CCT_LABEL:
+            case CCT_FUNCTION:
+            case CCT_EXCLUDED_MISSING:
+              break;
+            }
+        }
+    }
+
+  free (vars);
+  return true;
+
+error:
+  free (vars);
+  return false;
+}
+\f
+
+struct merge_item
+  {
+    const struct ctables_summary_spec_set *set;
+    size_t ofs;
+  };
+
+static int
+merge_item_compare_3way (const struct merge_item *a, const struct merge_item *b)
+{
+  const struct ctables_summary_spec *as = &a->set->specs[a->ofs];
+  const struct ctables_summary_spec *bs = &b->set->specs[b->ofs];
+  if (as->function != bs->function)
+    return as->function > bs->function ? 1 : -1;
+  else if (as->weighting != bs->weighting)
+    return as->weighting > bs->weighting ? 1 : -1;
+  else if (as->calc_area != bs->calc_area)
+    return as->calc_area > bs->calc_area ? 1 : -1;
+  else if (as->percentile != bs->percentile)
+    return as->percentile < bs->percentile ? 1 : -1;
+
+  const char *as_label = as->label ? as->label : "";
+  const char *bs_label = bs->label ? bs->label : "";
+  return strcmp (as_label, bs_label);
+}
+
+static void
+ctables_table_add_section (struct ctables_table *t, enum pivot_axis_type a,
+                           size_t ix[PIVOT_N_AXES])
+{
+  if (a < PIVOT_N_AXES)
+    {
+      size_t limit = MAX (t->stacks[a].n, 1);
+      for (ix[a] = 0; ix[a] < limit; ix[a]++)
+        ctables_table_add_section (t, a + 1, ix);
+    }
+  else
+    {
+      struct ctables_section *s = &t->sections[t->n_sections++];
+      *s = (struct ctables_section) {
+        .table = t,
+        .cells = HMAP_INITIALIZER (s->cells),
+      };
+      for (a = 0; a < PIVOT_N_AXES; a++)
+        if (t->stacks[a].n)
+          {
+            struct ctables_nest *nest = &t->stacks[a].nests[ix[a]];
+            s->nests[a] = nest;
+            s->occurrences[a] = xnmalloc (nest->n, sizeof *s->occurrences[a]);
+            for (size_t i = 0; i < nest->n; i++)
+              hmap_init (&s->occurrences[a][i]);
+        }
+      for (enum ctables_area_type at = 0; at < N_CTATS; at++)
+        hmap_init (&s->areas[at]);
+    }
+}
+
+static char *
+ctables_format (double d, const struct fmt_spec *format,
+                const struct fmt_settings *settings)
+{
+  const union value v = { .f = d };
+  char *s = data_out_stretchy (&v, "UTF-8", format, settings, NULL);
+
+  /* The custom-currency specifications for NEQUAL, PAREN, and PCTPAREN don't
+     produce the results we want for negative numbers, putting the negative
+     sign in the wrong spot, before the prefix instead of after it.  We can't,
+     in fact, produce the desired results using a custom-currency
+     specification.  Instead, we postprocess the output, moving the negative
+     sign into place:
+
+         NEQUAL:   "-N=3"  => "N=-3"
+         PAREN:    "-(3)"  => "(-3)"
+         PCTPAREN: "-(3%)" => "(-3%)"
+
+     This transformation doesn't affect NEGPAREN. */
+  char *minus_src = strchr (s, '-');
+  if (minus_src && (minus_src == s || minus_src[-1] != 'E'))
+    {
+      char *n_equals = strstr (s, "N=");
+      char *lparen = strchr (s, '(');
+      char *minus_dst = n_equals ? n_equals + 1 : lparen;
+      if (minus_dst)
+        move_element (s, minus_dst - s + 1, 1, minus_src - s, minus_dst - s);
+    }
+  return s;
+}
+
+static bool
+all_hidden_vlabels (const struct ctables_table *t, enum pivot_axis_type a)
+{
+  for (size_t i = 0; i < t->stacks[a].n; i++)
+    {
+      struct ctables_nest *nest = &t->stacks[a].nests[i];
+      if (nest->n != 1 || nest->scale_idx != 0)
+        return false;
+
+      enum ctables_vlabel vlabel
+        = t->ctables->vlabels[var_get_dict_index (nest->vars[0])];
+      if (vlabel != CTVL_NONE)
+        return false;
+    }
+  return true;
+}
+
+static void
+ctables_table_output (struct ctables *ct, struct ctables_table *t)
+{
+  struct pivot_table *pt = pivot_table_create__ (
+    (t->title
+     ? pivot_value_new_user_text (t->title, SIZE_MAX)
+     : pivot_value_new_text (N_("Custom Tables"))),
+    "Custom Tables");
+  if (t->caption)
+    pivot_table_set_caption (
+      pt, pivot_value_new_user_text (t->caption, SIZE_MAX));
+  if (t->corner)
+    pivot_table_set_corner_text (
+      pt, pivot_value_new_user_text (t->corner, SIZE_MAX));
+
+  bool summary_dimension = (t->summary_axis != t->slabels_axis
+                            || (!t->slabels_visible
+                                && t->summary_specs.n > 1));
+  if (summary_dimension)
+    {
+      struct pivot_dimension *d = pivot_dimension_create (
+        pt, t->slabels_axis, N_("Statistics"));
+      const struct ctables_summary_spec_set *specs = &t->summary_specs;
+      if (!t->slabels_visible)
+        d->hide_all_labels = true;
+      for (size_t i = 0; i < specs->n; i++)
+        pivot_category_create_leaf (
+          d->root, ctables_summary_label (&specs->specs[i], t->cilevel));
+    }
+
+  bool categories_dimension = t->clabels_example != NULL;
+  if (categories_dimension)
+    {
+      struct pivot_dimension *d = pivot_dimension_create (
+        pt, t->label_axis[t->clabels_from_axis],
+        t->clabels_from_axis == PIVOT_AXIS_ROW
+        ? N_("Row Categories")
+        : N_("Column Categories"));
+      const struct variable *var = t->clabels_example;
+      const struct ctables_categories *c = t->categories[var_get_dict_index (var)];
+      for (size_t i = 0; i < t->n_clabels_values; i++)
+        {
+          const struct ctables_value *value = t->clabels_values[i];
+          const struct ctables_category *cat = ctables_categories_match (c, &value->value, var);
+          assert (cat != NULL);
+          pivot_category_create_leaf (
+            d->root, ctables_category_create_value_label (c, cat,
+                                                          t->clabels_example,
+                                                          &value->value));
+        }
+    }
+
+  pivot_table_set_look (pt, ct->look);
+  struct pivot_dimension *d[PIVOT_N_AXES];
+  for (enum pivot_axis_type a = 0; a < PIVOT_N_AXES; a++)
+    {
+      static const char *names[] = {
+        [PIVOT_AXIS_ROW] = N_("Rows"),
+        [PIVOT_AXIS_COLUMN] = N_("Columns"),
+        [PIVOT_AXIS_LAYER] = N_("Layers"),
+      };
+      d[a] = (t->axes[a] || a == t->summary_axis
+              ? pivot_dimension_create (pt, a, names[a])
+              : NULL);
+      if (!d[a])
+        continue;
+
+      assert (t->axes[a]);
+
+      for (size_t i = 0; i < t->stacks[a].n; i++)
+        {
+          struct ctables_nest *nest = &t->stacks[a].nests[i];
+          struct ctables_section **sections = xnmalloc (t->n_sections,
+                                                        sizeof *sections);
+          size_t n_sections = 0;
+
+          size_t n_total_cells = 0;
+          size_t max_depth = 0;
+          for (size_t j = 0; j < t->n_sections; j++)
+            if (t->sections[j].nests[a] == nest)
+              {
+                struct ctables_section *s = &t->sections[j];
+                sections[n_sections++] = s;
+                n_total_cells += hmap_count (&s->cells);
+
+                size_t depth = s->nests[a]->n;
+                max_depth = MAX (depth, max_depth);
+              }
+
+          struct ctables_cell **sorted = xnmalloc (n_total_cells,
+                                                   sizeof *sorted);
+          size_t n_sorted = 0;
+
+          for (size_t j = 0; j < n_sections; j++)
+            {
+              struct ctables_section *s = sections[j];
+
+              struct ctables_cell *cell;
+              HMAP_FOR_EACH (cell, struct ctables_cell, node, &s->cells)
+                if (!cell->hide)
+                  sorted[n_sorted++] = cell;
+              assert (n_sorted <= n_total_cells);
+            }
+
+          struct ctables_cell_sort_aux aux = { .nest = nest, .a = a };
+          sort (sorted, n_sorted, sizeof *sorted, ctables_cell_compare_3way, &aux);
+
+          struct ctables_level
+            {
+              enum ctables_level_type
+                {
+                  CTL_VAR,          /* Variable label for nest->vars[var_idx]. */
+                  CTL_CATEGORY,     /* Category for nest->vars[var_idx]. */
+                  CTL_SUMMARY,      /* Summary functions. */
+                }
+                type;
+
+              enum settings_value_show vlabel; /* CTL_VAR only. */
+              size_t var_idx;
+            };
+          struct ctables_level *levels = xnmalloc (1 + 2 * max_depth, sizeof *levels);
+          size_t n_levels = 0;
+          for (size_t k = 0; k < nest->n; k++)
+            {
+              enum ctables_vlabel vlabel = ct->vlabels[var_get_dict_index (nest->vars[k])];
+              if (vlabel == CTVL_NONE && nest->scale_idx == k)
+                vlabel = CTVL_NAME;
+              if (vlabel != CTVL_NONE)
+                {
+                  levels[n_levels++] = (struct ctables_level) {
+                    .type = CTL_VAR,
+                    .vlabel = (enum settings_value_show) vlabel,
+                    .var_idx = k,
+                  };
+                }
+
+              if (nest->scale_idx != k
+                  && (k != nest->n - 1 || t->label_axis[a] == a))
+                {
+                  levels[n_levels++] = (struct ctables_level) {
+                    .type = CTL_CATEGORY,
+                    .var_idx = k,
+                  };
+                }
+            }
+
+          if (!summary_dimension && a == t->slabels_axis)
+            {
+              levels[n_levels++] = (struct ctables_level) {
+                .type = CTL_SUMMARY,
+                .var_idx = SIZE_MAX,
+              };
+            }
+
+          /* Pivot categories:
+
+             - variable label for nest->vars[0], if vlabel != CTVL_NONE
+             - category for nest->vars[0], if nest->scale_idx != 0
+             - variable label for nest->vars[1], if vlabel != CTVL_NONE
+             - category for nest->vars[1], if nest->scale_idx != 1
+             ...
+             - variable label for nest->vars[n - 1], if vlabel != CTVL_NONE
+             - category for nest->vars[n - 1], if t->label_axis[a] == a && nest->scale_idx != n - 1.
+             - summary function, if 'a == t->slabels_axis && a ==
+             t->summary_axis'.
+
+             Additional dimensions:
+
+             - If 'a == t->slabels_axis && a != t->summary_axis', add a summary
+             dimension.
+             - If 't->label_axis[b] == a' for some 'b != a', add a category
+             dimension to 'a'.
+          */
+
+
+          struct pivot_category **groups = xnmalloc (1 + 2 * max_depth, sizeof *groups);
+          int prev_leaf = 0;
+          for (size_t j = 0; j < n_sorted; j++)
+            {
+              struct ctables_cell *cell = sorted[j];
+              struct ctables_cell *prev = j > 0 ? sorted[j - 1] : NULL;
+
+              size_t n_common = 0;
+              if (j > 0)
+                {
+                  for (; n_common < n_levels; n_common++)
+                    {
+                      const struct ctables_level *level = &levels[n_common];
+                      if (level->type == CTL_CATEGORY)
+                        {
+                          size_t var_idx = level->var_idx;
+                          const struct ctables_category *c = cell->axes[a].cvs[var_idx].category;
+                          if (prev->axes[a].cvs[var_idx].category != c)
+                            break;
+                          else if (c->type != CCT_SUBTOTAL
+                                   && c->type != CCT_TOTAL
+                                   && c->type != CCT_POSTCOMPUTE
+                                   && !value_equal (&prev->axes[a].cvs[var_idx].value,
+                                                    &cell->axes[a].cvs[var_idx].value,
+                                                    var_get_type (nest->vars[var_idx])))
+                            break;
+                        }
+                    }
+                }
+
+              for (size_t k = n_common; k < n_levels; k++)
+                {
+                  const struct ctables_level *level = &levels[k];
+                  struct pivot_category *parent = k ? groups[k - 1] : d[a]->root;
+                  if (level->type == CTL_SUMMARY)
+                    {
+                      assert (k == n_levels - 1);
+
+                      const struct ctables_summary_spec_set *specs = &t->summary_specs;
+                      for (size_t m = 0; m < specs->n; m++)
+                        {
+                          int leaf = pivot_category_create_leaf (
+                            parent, ctables_summary_label (&specs->specs[m],
+                                                           t->cilevel));
+                          if (!m)
+                            prev_leaf = leaf;
+                        }
+                    }
+                  else
+                    {
+                      const struct variable *var = nest->vars[level->var_idx];
+                      struct pivot_value *label;
+                      if (level->type == CTL_VAR)
+                        {
+                          label = pivot_value_new_variable (var);
+                          label->variable.show = level->vlabel;
+                        }
+                      else if (level->type == CTL_CATEGORY)
+                        {
+                          const struct ctables_cell_value *cv = &cell->axes[a].cvs[level->var_idx];
+                          label = ctables_category_create_value_label (
+                            t->categories[var_get_dict_index (var)],
+                            cv->category, var, &cv->value);
+                        }
+                      else
+                        NOT_REACHED ();
+
+                      if (k == n_levels - 1)
+                        prev_leaf = pivot_category_create_leaf (parent, label);
+                      else
+                        groups[k] = pivot_category_create_group__ (parent, label);
+                    }
+                }
+
+              cell->axes[a].leaf = prev_leaf;
+            }
+          free (sorted);
+          free (groups);
+          free (levels);
+          free (sections);
+
+        }
+
+      d[a]->hide_all_labels = all_hidden_vlabels (t, a);
+    }
+
+  {
+    size_t n_total_cells = 0;
+    for (size_t j = 0; j < t->n_sections; j++)
+      n_total_cells += hmap_count (&t->sections[j].cells);
+
+    struct ctables_cell **sorted = xnmalloc (n_total_cells, sizeof *sorted);
+    size_t n_sorted = 0;
+    for (size_t j = 0; j < t->n_sections; j++)
+      {
+        const struct ctables_section *s = &t->sections[j];
+        struct ctables_cell *cell;
+        HMAP_FOR_EACH (cell, struct ctables_cell, node, &s->cells)
+          if (!cell->hide)
+            sorted[n_sorted++] = cell;
+      }
+    assert (n_sorted <= n_total_cells);
+    sort (sorted, n_sorted, sizeof *sorted, ctables_cell_compare_leaf_3way,
+          NULL);
+    size_t ids[N_CTATS];
+    memset (ids, 0, sizeof ids);
+    for (size_t j = 0; j < n_sorted; j++)
+      {
+        struct ctables_cell *cell = sorted[j];
+        for (enum ctables_area_type at = 0; at < N_CTATS; at++)
+          {
+            struct ctables_area *area = cell->areas[at];
+            if (!area->sequence)
+              area->sequence = ++ids[at];
+          }
+      }
+
+    free (sorted);
+  }
+
+  for (size_t i = 0; i < t->n_sections; i++)
+    {
+      struct ctables_section *s = &t->sections[i];
+
+      struct ctables_cell *cell;
+      HMAP_FOR_EACH (cell, struct ctables_cell, node, &s->cells)
+        {
+          if (cell->hide)
+            continue;
+
+          const struct ctables_nest *specs_nest = s->nests[t->summary_axis];
+          const struct ctables_summary_spec_set *specs = &specs_nest->specs[cell->sv];
+          for (size_t j = 0; j < specs->n; j++)
+            {
+              size_t dindexes[5];
+              size_t n_dindexes = 0;
+
+              if (summary_dimension)
+                dindexes[n_dindexes++] = specs->specs[j].axis_idx;
+
+              if (categories_dimension)
+                {
+                  const struct ctables_nest *clabels_nest = s->nests[t->clabels_from_axis];
+                  const struct variable *var = clabels_nest->vars[clabels_nest->n - 1];
+                  const union value *value = &cell->axes[t->clabels_from_axis].cvs[clabels_nest->n - 1].value;
+                  const struct ctables_value *ctv = ctables_value_find (t, value, var_get_width (var));
+                  if (!ctv)
+                    continue;
+                  dindexes[n_dindexes++] = ctv->leaf;
+                }
+
+              for (enum pivot_axis_type a = 0; a < PIVOT_N_AXES; a++)
+                if (d[a])
+                  {
+                    int leaf = cell->axes[a].leaf;
+                    if (a == t->summary_axis && !summary_dimension)
+                      leaf += j;
+                    dindexes[n_dindexes++] = leaf;
+                  }
+
+              const struct ctables_summary_spec *ss = &specs->specs[j];
+
+              struct fmt_spec format = specs->specs[j].format;
+              bool is_ctables_format = ss->is_ctables_format;
+              double d = (cell->postcompute
+                          ? ctables_cell_calculate_postcompute (
+                            s, cell, ss, &format, &is_ctables_format, j)
+                          : ctables_summary_value (cell->areas,
+                                                   &cell->summaries[j], ss));
+
+              struct pivot_value *value;
+              if (ct->hide_threshold != 0
+                  && d < ct->hide_threshold
+                  && ss->function == CTSF_COUNT)
+                {
+                  value = pivot_value_new_user_text_nocopy (
+                    xasprintf ("<%d", ct->hide_threshold));
+                }
+              else if (d == 0 && ct->zero)
+                value = pivot_value_new_user_text (ct->zero, SIZE_MAX);
+              else if (d == SYSMIS && ct->missing)
+                value = pivot_value_new_user_text (ct->missing, SIZE_MAX);
+              else if (is_ctables_format)
+                value = pivot_value_new_user_text_nocopy (
+                  ctables_format (d, &format, &ct->ctables_formats));
+              else
+                {
+                  value = pivot_value_new_number (d);
+                  value->numeric.format = format;
+                }
+              /* XXX should text values be right-justified? */
+              pivot_table_put (pt, dindexes, n_dindexes, value);
+            }
+        }
+    }
+
+  pivot_table_submit (pt);
+}
+
+static bool
+ctables_check_label_position (struct ctables_table *t, enum pivot_axis_type a)
+{
+  enum pivot_axis_type label_pos = t->label_axis[a];
+  if (label_pos == a)
+    return true;
+
+  const char *subcommand_name = a == PIVOT_AXIS_ROW ? "ROWLABELS" : "COLLABELS";
+  const char *pos_name = label_pos == PIVOT_AXIS_LAYER ? "LAYER" : "OPPOSITE";
+
+  const struct ctables_stack *stack = &t->stacks[a];
+  if (!stack->n)
+    return true;
+
+  const struct ctables_nest *n0 = &stack->nests[0];
+  if (n0->n == 0)
+    {
+      assert (stack->n == 1);
+      return true;
+    }
+
+  const struct variable *v0 = n0->vars[n0->n - 1];
+  struct ctables_categories *c0 = t->categories[var_get_dict_index (v0)];
+  t->clabels_example = v0;
+
+  for (size_t i = 0; i < c0->n_cats; i++)
+    if (c0->cats[i].type == CCT_FUNCTION)
+      {
+        msg (SE, _("%s=%s is not allowed with sorting based "
+                   "on a summary function."),
+             subcommand_name, pos_name);
+        return false;
+      }
+  if (n0->n - 1 == n0->scale_idx)
+    {
+      msg (SE, _("%s=%s requires the variables to be moved to be categorical, "
+                 "but %s is a scale variable."),
+           subcommand_name, pos_name, var_get_name (v0));
+      return false;
+    }
+
+  for (size_t i = 1; i < stack->n; i++)
+    {
+      const struct ctables_nest *ni = &stack->nests[i];
+      assert (ni->n > 0);
+      const struct variable *vi = ni->vars[ni->n - 1];
+      struct ctables_categories *ci = t->categories[var_get_dict_index (vi)];
+
+      if (ni->n - 1 == ni->scale_idx)
+        {
+          msg (SE, _("%s=%s requires the variables to be moved to be "
+                     "categorical, but %s is a scale variable."),
+               subcommand_name, pos_name, var_get_name (vi));
+          return false;
+        }
+      if (var_get_width (v0) != var_get_width (vi))
+        {
+          msg (SE, _("%s=%s requires the variables to be "
+                     "moved to have the same width, but %s has "
+                     "width %d and %s has width %d."),
+               subcommand_name, pos_name,
+               var_get_name (v0), var_get_width (v0),
+               var_get_name (vi), var_get_width (vi));
+          return false;
+        }
+      if (!val_labs_equal (var_get_value_labels (v0),
+                           var_get_value_labels (vi)))
+        {
+          msg (SE, _("%s=%s requires the variables to be "
+                     "moved to have the same value labels, but %s "
+                     "and %s have different value labels."),
+               subcommand_name, pos_name,
+               var_get_name (v0), var_get_name (vi));
+          return false;
+        }
+      if (!ctables_categories_equal (c0, ci))
+        {
+          msg (SE, _("%s=%s requires the variables to be "
+                     "moved to have the same category "
+                     "specifications, but %s and %s have different "
+                     "category specifications."),
+               subcommand_name, pos_name,
+               var_get_name (v0), var_get_name (vi));
+          return false;
+        }
+    }
+
+  return true;
+}
+
+static size_t
+add_sum_var (struct variable *var,
+             struct variable ***sum_vars, size_t *n, size_t *allocated)
+{
+  for (size_t i = 0; i < *n; i++)
+    if (var == (*sum_vars)[i])
+      return i;
+
+  if (*n >= *allocated)
+    *sum_vars = x2nrealloc (*sum_vars, allocated, sizeof **sum_vars);
+  (*sum_vars)[*n] = var;
+  return (*n)++;
+}
+
+static enum ctables_area_type
+rotate_area (enum ctables_area_type area)
+{
+  return area;
+  switch (area)
+    {
+    case CTAT_TABLE:
+    case CTAT_LAYER:
+    case CTAT_SUBTABLE:
+      return area;
+
+    case CTAT_LAYERROW:
+      return CTAT_LAYERCOL;
+
+    case CTAT_LAYERCOL:
+      return CTAT_LAYERROW;
+
+    case CTAT_ROW:
+      return CTAT_COL;
+
+    case CTAT_COL:
+      return CTAT_ROW;
+    }
+
+  NOT_REACHED ();
+}
+
+static void
+enumerate_sum_vars (const struct ctables_axis *a,
+                    struct variable ***sum_vars, size_t *n, size_t *allocated)
+{
+  if (!a)
+    return;
+
+  switch (a->op)
+    {
+    case CTAO_VAR:
+      for (size_t i = 0; i < N_CSVS; i++)
+        for (size_t j = 0; j < a->specs[i].n; j++)
+          {
+            struct ctables_summary_spec *spec = &a->specs[i].specs[j];
+            if (spec->function == CTSF_areaPCT_SUM)
+              spec->sum_var_idx = add_sum_var (a->var, sum_vars, n, allocated);
+          }
+      break;
+
+    case CTAO_STACK:
+    case CTAO_NEST:
+      for (size_t i = 0; i < 2; i++)
+        enumerate_sum_vars (a->subs[i], sum_vars, n, allocated);
+      break;
+    }
+}
+
+static bool
+ctables_prepare_table (struct ctables_table *t)
+{
+  for (enum pivot_axis_type a = 0; a < PIVOT_N_AXES; a++)
+    if (t->axes[a])
+      {
+        t->stacks[a] = enumerate_fts (a, t->axes[a]);
+
+        for (size_t j = 0; j < t->stacks[a].n; j++)
+          {
+            struct ctables_nest *nest = &t->stacks[a].nests[j];
+            for (enum ctables_area_type at = 0; at < N_CTATS; at++)
+              {
+                nest->areas[at] = xmalloc (nest->n * sizeof *nest->areas[at]);
+                nest->n_areas[at] = 0;
+
+                enum pivot_axis_type ata, atb;
+                if (at == CTAT_ROW || at == CTAT_LAYERROW)
+                  {
+                    ata = PIVOT_AXIS_ROW;
+                    atb = PIVOT_AXIS_COLUMN;
+                  }
+                else if (at == CTAT_COL || at == CTAT_LAYERCOL)
+                  {
+                    ata = PIVOT_AXIS_COLUMN;
+                    atb = PIVOT_AXIS_ROW;
+                  }
+
+                if (at == CTAT_LAYER
+                    ? a != PIVOT_AXIS_LAYER && t->label_axis[a] == PIVOT_AXIS_LAYER
+                    : at == CTAT_LAYERCOL || at == CTAT_LAYERROW
+                    ? a == atb && t->label_axis[a] != a
+                    : false)
+                  {
+                    for (size_t k = nest->n - 1; k < nest->n; k--)
+                      if (k != nest->scale_idx)
+                        {
+                          nest->areas[at][nest->n_areas[at]++] = k;
+                          break;
+                        }
+                    continue;
+                  }
+
+                if (at == CTAT_LAYER ? a != PIVOT_AXIS_LAYER
+                    : at == CTAT_LAYERROW || at == CTAT_LAYERCOL ? a == atb
+                    : at == CTAT_TABLE ? true
+                    : false)
+                  continue;
+
+                for (size_t k = 0; k < nest->n; k++)
+                  if (k != nest->scale_idx)
+                    nest->areas[at][nest->n_areas[at]++] = k;
+
+                int n_drop;
+                switch (at)
+                  {
+                  case CTAT_SUBTABLE:
+#define L PIVOT_AXIS_LAYER
+                    n_drop = (t->clabels_from_axis == L ? a != L
+                              : t->clabels_to_axis == L ? (t->clabels_from_axis == a ? -1 : a != L)
+                              : t->clabels_from_axis == a ? 2
+                              : 0);
+#undef L
+                    break;
+
+                  case CTAT_LAYERROW:
+                  case CTAT_LAYERCOL:
+                    n_drop = a == ata && t->label_axis[ata] == atb;
+                    break;
+
+                  case CTAT_ROW:
+                  case CTAT_COL:
+                    n_drop = (a == ata ? t->label_axis[ata] == atb
+                              : a != atb ? 0
+                              : t->clabels_from_axis == atb ? -1
+                              : t->clabels_to_axis != atb ? 1
+                              : 0);
+                    break;
+
+                  case CTAT_LAYER:
+                  case CTAT_TABLE:
+                    n_drop = 0;
+                    break;
+                  }
+
+                if (n_drop < 0)
+                  {
+                    size_t n = nest->n_areas[at];
+                    if (n > 1)
+                      {
+                        nest->areas[at][n - 2] = nest->areas[at][n - 1];
+                        nest->n_areas[at]--;
+                      }
+                  }
+                else
+                  {
+                    for (int i = 0; i < n_drop; i++)
+                      if (nest->n_areas[at] > 0)
+                        nest->n_areas[at]--;
+                  }
+              }
+          }
+      }
+    else
+      {
+        struct ctables_nest *nest = xmalloc (sizeof *nest);
+        *nest = (struct ctables_nest) {
+          .n = 0,
+          .scale_idx = SIZE_MAX,
+          .summary_idx = SIZE_MAX
+        };
+        t->stacks[a] = (struct ctables_stack) { .nests = nest, .n = 1 };
+
+        /* There's no point in moving labels away from an axis that has no
+           labels, so avoid dealing with the special cases around that. */
+        t->label_axis[a] = a;
+      }
+
+  struct ctables_stack *stack = &t->stacks[t->summary_axis];
+  for (size_t i = 0; i < stack->n; i++)
+    {
+      struct ctables_nest *nest = &stack->nests[i];
+      if (!nest->specs[CSV_CELL].n)
+        {
+          struct ctables_summary_spec_set *ss = &nest->specs[CSV_CELL];
+          ss->specs = xmalloc (sizeof *ss->specs);
+          ss->n = 1;
+
+          enum ctables_summary_function function
+            = ss->is_scale ? CTSF_MEAN : CTSF_COUNT;
+
+          if (!ss->var)
+            {
+              nest->summary_idx = nest->n - 1;
+              ss->var = nest->vars[nest->summary_idx];
+            }
+          *ss->specs = (struct ctables_summary_spec) {
+            .function = function,
+            .weighting = ss->is_scale ? CTW_EFFECTIVE : CTW_DICTIONARY,
+            .format = ctables_summary_default_format (function, ss->var),
+          };
+
+          ctables_summary_spec_set_clone (&nest->specs[CSV_TOTAL],
+                                          &nest->specs[CSV_CELL]);
+        }
+      else if (!nest->specs[CSV_TOTAL].n)
+        ctables_summary_spec_set_clone (&nest->specs[CSV_TOTAL],
+                                        &nest->specs[CSV_CELL]);
+
+      if (t->label_axis[PIVOT_AXIS_ROW] == PIVOT_AXIS_COLUMN
+          || t->label_axis[PIVOT_AXIS_COLUMN] == PIVOT_AXIS_ROW)
+        {
+          for (enum ctables_summary_variant sv = 0; sv < N_CSVS; sv++)
+            for (size_t i = 0; i < nest->specs[sv].n; i++)
+              {
+                struct ctables_summary_spec *ss = &nest->specs[sv].specs[i];
+                const struct ctables_function_info *cfi =
+                  &ctables_function_info[ss->function];
+                if (cfi->is_area)
+                  ss->calc_area = rotate_area (ss->calc_area);
+              }
+        }
+
+      if (t->ctables->smissing_listwise)
+        {
+          struct variable **listwise_vars = NULL;
+          size_t n = 0;
+          size_t allocated = 0;
+
+          for (size_t j = nest->group_head; j < stack->n; j++)
+            {
+              const struct ctables_nest *other_nest = &stack->nests[j];
+              if (other_nest->group_head != nest->group_head)
+                break;
+
+              if (nest != other_nest && other_nest->scale_idx < other_nest->n)
+                {
+                  if (n >= allocated)
+                    listwise_vars = x2nrealloc (listwise_vars, &allocated,
+                                                sizeof *listwise_vars);
+                  listwise_vars[n++] = other_nest->vars[other_nest->scale_idx];
+                }
+            }
+          for (enum ctables_summary_variant sv = 0; sv < N_CSVS; sv++)
+            {
+              if (sv > 0)
+                listwise_vars = xmemdup (listwise_vars,
+                                         n * sizeof *listwise_vars);
+              nest->specs[sv].listwise_vars = listwise_vars;
+              nest->specs[sv].n_listwise_vars = n;
+            }
+        }
+    }
+
+  struct ctables_summary_spec_set *merged = &t->summary_specs;
+  struct merge_item *items = xnmalloc (N_CSVS * stack->n, sizeof *items);
+  size_t n_left = 0;
+  for (size_t j = 0; j < stack->n; j++)
+    {
+      const struct ctables_nest *nest = &stack->nests[j];
+      if (nest->n)
+        for (enum ctables_summary_variant sv = 0; sv < N_CSVS; sv++)
+          items[n_left++] = (struct merge_item) { .set = &nest->specs[sv] };
+    }
+
+  while (n_left > 0)
+    {
+      struct merge_item min = items[0];
+      for (size_t j = 1; j < n_left; j++)
+        if (merge_item_compare_3way (&items[j], &min) < 0)
+          min = items[j];
+
+      if (merged->n >= merged->allocated)
+        merged->specs = x2nrealloc (merged->specs, &merged->allocated,
+                                    sizeof *merged->specs);
+      merged->specs[merged->n++] = min.set->specs[min.ofs];
+
+      for (size_t j = 0; j < n_left; )
+        {
+          if (merge_item_compare_3way (&items[j], &min) == 0)
+            {
+              struct merge_item *item = &items[j];
+              item->set->specs[item->ofs++].axis_idx = merged->n - 1;
+              if (item->ofs >= item->set->n)
+                {
+                  items[j] = items[--n_left];
+                  continue;
+                }
+            }
+          j++;
+        }
+    }
+  free (items);
+
+  size_t allocated_sum_vars = 0;
+  enumerate_sum_vars (t->axes[t->summary_axis],
+                      &t->sum_vars, &t->n_sum_vars, &allocated_sum_vars);
+
+  return (ctables_check_label_position (t, PIVOT_AXIS_ROW)
+          && ctables_check_label_position (t, PIVOT_AXIS_COLUMN));
+}
+
+static void
+ctables_insert_clabels_values (struct ctables_table *t, const struct ccase *c,
+                               enum pivot_axis_type a)
+{
+  struct ctables_stack *stack = &t->stacks[a];
+  for (size_t i = 0; i < stack->n; i++)
+    {
+      const struct ctables_nest *nest = &stack->nests[i];
+      const struct variable *var = nest->vars[nest->n - 1];
+      const union value *value = case_data (c, var);
+
+      if (var_is_numeric (var) && value->f == SYSMIS)
+        continue;
+
+      if (ctables_categories_match (t->categories [var_get_dict_index (var)],
+                                    value, var))
+        ctables_value_insert (t, value, var_get_width (var));
+    }
+}
+
+static void
+ctables_add_category_occurrences (const struct variable *var,
+                                  struct hmap *occurrences,
+                                  const struct ctables_categories *cats)
+{
+  const struct val_labs *val_labs = var_get_value_labels (var);
+
+  for (size_t i = 0; i < cats->n_cats; i++)
+    {
+      const struct ctables_category *c = &cats->cats[i];
+      switch (c->type)
+        {
+        case CCT_NUMBER:
+          ctables_add_occurrence (var, &(const union value) { .f = c->number },
+                                  occurrences);
+          break;
+
+        case CCT_STRING:
+          {
+            int width = var_get_width (var);
+            union value value;
+            value_init (&value, width);
+            value_copy_buf_rpad (&value, width,
+                                 CHAR_CAST (uint8_t *, c->string.string),
+                                 c->string.length, ' ');
+            ctables_add_occurrence (var, &value, occurrences);
+            value_destroy (&value, width);
+          }
+          break;
+
+        case CCT_NRANGE:
+          assert (var_is_numeric (var));
+          for (const struct val_lab *vl = val_labs_first (val_labs); vl;
+               vl = val_labs_next (val_labs, vl))
+            if (vl->value.f >= c->nrange[0] && vl->value.f <= c->nrange[1])
+              ctables_add_occurrence (var, &vl->value, occurrences);
+          break;
+
+        case CCT_SRANGE:
+          assert (var_is_alpha (var));
+          for (const struct val_lab *vl = val_labs_first (val_labs); vl;
+               vl = val_labs_next (val_labs, vl))
+            if (in_string_range (&vl->value, var, c->srange))
+              ctables_add_occurrence (var, &vl->value, occurrences);
+          break;
+
+        case CCT_MISSING:
+          for (const struct val_lab *vl = val_labs_first (val_labs); vl;
+               vl = val_labs_next (val_labs, vl))
+            if (var_is_value_missing (var, &vl->value))
+              ctables_add_occurrence (var, &vl->value, occurrences);
+          break;
+
+        case CCT_OTHERNM:
+          for (const struct val_lab *vl = val_labs_first (val_labs); vl;
+               vl = val_labs_next (val_labs, vl))
+            ctables_add_occurrence (var, &vl->value, occurrences);
+          break;
+
+        case CCT_POSTCOMPUTE:
+          break;
+
+        case CCT_SUBTOTAL:
+        case CCT_TOTAL:
+          break;
+
+        case CCT_VALUE:
+        case CCT_LABEL:
+        case CCT_FUNCTION:
+          for (const struct val_lab *vl = val_labs_first (val_labs); vl;
+               vl = val_labs_next (val_labs, vl))
+            if (c->include_missing || !var_is_value_missing (var, &vl->value))
+              ctables_add_occurrence (var, &vl->value, occurrences);
+          break;
+
+        case CCT_EXCLUDED_MISSING:
+          break;
+        }
+    }
+}
+
+static void
+ctables_section_recurse_add_empty_categories (
+  struct ctables_section *s,
+  const struct ctables_category **cats[PIVOT_N_AXES], struct ccase *c,
+  enum pivot_axis_type a, size_t a_idx)
+{
+  if (a >= PIVOT_N_AXES)
+    ctables_cell_insert__ (s, c, cats);
+  else if (!s->nests[a] || a_idx >= s->nests[a]->n)
+    ctables_section_recurse_add_empty_categories (s, cats, c, a + 1, 0);
+  else
+    {
+      const struct variable *var = s->nests[a]->vars[a_idx];
+      const struct ctables_categories *categories = s->table->categories[
+        var_get_dict_index (var)];
+      int width = var_get_width (var);
+      const struct hmap *occurrences = &s->occurrences[a][a_idx];
+      const struct ctables_occurrence *o;
+      HMAP_FOR_EACH (o, struct ctables_occurrence, node, occurrences)
+        {
+          union value *value = case_data_rw (c, var);
+          value_destroy (value, width);
+          value_clone (value, &o->value, width);
+          cats[a][a_idx] = ctables_categories_match (categories, value, var);
+          assert (cats[a][a_idx] != NULL);
+          ctables_section_recurse_add_empty_categories (s, cats, c, a, a_idx + 1);
+        }
+
+      for (size_t i = 0; i < categories->n_cats; i++)
+        {
+          const struct ctables_category *cat = &categories->cats[i];
+          if (cat->type == CCT_POSTCOMPUTE)
+            {
+              cats[a][a_idx] = cat;
+              ctables_section_recurse_add_empty_categories (s, cats, c, a, a_idx + 1);
+            }
+        }
+    }
+}
+
+static void
+ctables_section_add_empty_categories (struct ctables_section *s)
+{
+  bool show_empty = false;
+  for (size_t a = 0; a < PIVOT_N_AXES; a++)
+    if (s->nests[a])
+      for (size_t k = 0; k < s->nests[a]->n; k++)
+        if (k != s->nests[a]->scale_idx)
+          {
+            const struct variable *var = s->nests[a]->vars[k];
+            const struct ctables_categories *cats = s->table->categories[
+              var_get_dict_index (var)];
+            if (cats->show_empty)
+              {
+                show_empty = true;
+                ctables_add_category_occurrences (var, &s->occurrences[a][k], cats);
+              }
+          }
+  if (!show_empty)
+    return;
+
+  const struct ctables_category *layer_cats[s->nests[PIVOT_AXIS_LAYER]->n];
+  const struct ctables_category *row_cats[s->nests[PIVOT_AXIS_ROW]->n];
+  const struct ctables_category *column_cats[s->nests[PIVOT_AXIS_COLUMN]->n];
+  const struct ctables_category **cats[PIVOT_N_AXES] =
+    {
+      [PIVOT_AXIS_LAYER] = layer_cats,
+      [PIVOT_AXIS_ROW] = row_cats,
+      [PIVOT_AXIS_COLUMN] = column_cats,
+    };
+  struct ccase *c = case_create (dict_get_proto (s->table->ctables->dict));
+  ctables_section_recurse_add_empty_categories (s, cats, c, 0, 0);
+  case_unref (c);
+}
+
+static void
+ctables_section_clear (struct ctables_section *s)
+{
+  for (enum pivot_axis_type a = 0; a < PIVOT_N_AXES; a++)
+    {
+      const struct ctables_nest *nest = s->nests[a];
+      for (size_t i = 0; i < nest->n; i++)
+        if (i != nest->scale_idx)
+          {
+            const struct variable *var = nest->vars[i];
+            int width = var_get_width (var);
+            struct ctables_occurrence *o, *next;
+            struct hmap *map = &s->occurrences[a][i];
+            HMAP_FOR_EACH_SAFE (o, next, struct ctables_occurrence, node, map)
+              {
+                value_destroy (&o->value, width);
+                hmap_delete (map, &o->node);
+                free (o);
+              }
+            hmap_shrink (map);
+          }
+    }
+
+  struct ctables_cell *cell, *next_cell;
+  HMAP_FOR_EACH_SAFE (cell, next_cell, struct ctables_cell, node, &s->cells)
+    {
+      for (enum pivot_axis_type a = 0; a < PIVOT_N_AXES; a++)
+        {
+          const struct ctables_nest *nest = s->nests[a];
+          for (size_t i = 0; i < nest->n; i++)
+            if (i != nest->scale_idx)
+              value_destroy (&cell->axes[a].cvs[i].value,
+                             var_get_width (nest->vars[i]));
+          free (cell->axes[a].cvs);
+        }
+
+      const struct ctables_nest *ss = s->nests[s->table->summary_axis];
+      const struct ctables_summary_spec_set *specs = &ss->specs[cell->sv];
+      for (size_t i = 0; i < specs->n; i++)
+        ctables_summary_uninit (&cell->summaries[i], &specs->specs[i]);
+      free (cell->summaries);
+
+      hmap_delete (&s->cells, &cell->node);
+      free (cell);
+    }
+  hmap_shrink (&s->cells);
+
+  for (enum ctables_area_type at = 0; at < N_CTATS; at++)
+    {
+      struct ctables_area *area, *next_area;
+      HMAP_FOR_EACH_SAFE (area, next_area, struct ctables_area, node,
+                          &s->areas[at])
+        {
+          free (area->sums);
+          hmap_delete (&s->areas[at], &area->node);
+          free (area);
+        }
+      hmap_shrink (&s->areas[at]);
+    }
+}
+
+static void
+ctables_section_uninit (struct ctables_section *s)
+{
+  ctables_section_clear (s);
+
+  for (enum pivot_axis_type a = 0; a < PIVOT_N_AXES; a++)
+    {
+      struct ctables_nest *nest = s->nests[a];
+      for (size_t i = 0; i < nest->n; i++)
+        hmap_destroy (&s->occurrences[a][i]);
+      free (s->occurrences[a]);
+    }
+
+  hmap_destroy (&s->cells);
+  for (enum ctables_area_type at = 0; at < N_CTATS; at++)
+    hmap_destroy (&s->areas[at]);
+}
+
+static void
+ctables_table_clear (struct ctables_table *t)
+{
+  for (size_t i = 0; i < t->n_sections; i++)
+    ctables_section_clear (&t->sections[i]);
+
+  if (t->clabels_example)
+    {
+      int width = var_get_width (t->clabels_example);
+      struct ctables_value *value, *next_value;
+      HMAP_FOR_EACH_SAFE (value, next_value, struct ctables_value, node,
+                          &t->clabels_values_map)
+        {
+          value_destroy (&value->value, width);
+          hmap_delete (&t->clabels_values_map, &value->node);
+          free (value);
+        }
+      hmap_shrink (&t->clabels_values_map);
+
+      free (t->clabels_values);
+      t->clabels_values = NULL;
+      t->n_clabels_values = 0;
+    }
+}
+
+static bool
+ctables_execute (struct dataset *ds, struct casereader *input,
+                 struct ctables *ct)
+{
+  for (size_t i = 0; i < ct->n_tables; i++)
+    {
+      struct ctables_table *t = ct->tables[i];
+      t->sections = xnmalloc (MAX (1, t->stacks[PIVOT_AXIS_ROW].n) *
+                              MAX (1, t->stacks[PIVOT_AXIS_COLUMN].n) *
+                              MAX (1, t->stacks[PIVOT_AXIS_LAYER].n),
+                              sizeof *t->sections);
+      size_t ix[PIVOT_N_AXES];
+      ctables_table_add_section (t, 0, ix);
+    }
+
+  struct dictionary *dict = dataset_dict (ds);
+
+  bool splitting = dict_get_split_type (dict) == SPLIT_SEPARATE;
+  struct casegrouper *grouper
+    = (splitting
+       ? casegrouper_create_splits (input, dict)
+       : casegrouper_create_vars (input, NULL, 0));
+  struct casereader *group;
+  while (casegrouper_get_next_group (grouper, &group))
+    {
+      if (splitting)
+        {
+          struct ccase *c = casereader_peek (group, 0);
+          if (c != NULL)
+            {
+              output_split_file_values (ds, c);
+              case_unref (c);
+            }
+        }
+
+      bool warn_on_invalid = true;
+      for (struct ccase *c = casereader_read (group); c;
+           case_unref (c), c = casereader_read (group))
+        {
+          double d_weight = dict_get_rounded_case_weight (dict, c, &warn_on_invalid);
+          double e_weight = (ct->e_weight
+                             ? var_force_valid_weight (ct->e_weight,
+                                                       case_num (c, ct->e_weight),
+                                                       &warn_on_invalid)
+                             : d_weight);
+          double weight[] = {
+            [CTW_DICTIONARY] = d_weight,
+            [CTW_EFFECTIVE] = e_weight,
+            [CTW_UNWEIGHTED] = 1.0,
+          };
+
+          for (size_t i = 0; i < ct->n_tables; i++)
+            {
+              struct ctables_table *t = ct->tables[i];
+
+              for (size_t j = 0; j < t->n_sections; j++)
+                ctables_cell_insert (&t->sections[j], c, weight);
+
+              for (enum pivot_axis_type a = 0; a < PIVOT_N_AXES; a++)
+                if (t->label_axis[a] != a)
+                  ctables_insert_clabels_values (t, c, a);
+            }
+        }
+      casereader_destroy (group);
+
+      for (size_t i = 0; i < ct->n_tables; i++)
+        {
+          struct ctables_table *t = ct->tables[i];
+
+          if (t->clabels_example)
+            ctables_sort_clabels_values (t);
+
+          for (size_t j = 0; j < t->n_sections; j++)
+            ctables_section_add_empty_categories (&t->sections[j]);
+
+          ctables_table_output (ct, t);
+          ctables_table_clear (t);
+        }
+    }
+  return casegrouper_destroy (grouper);
+}
+\f
+static struct ctables_postcompute *
+ctables_find_postcompute (struct ctables *ct, const char *name)
+{
+  struct ctables_postcompute *pc;
+  HMAP_FOR_EACH_WITH_HASH (pc, struct ctables_postcompute, hmap_node,
+                           utf8_hash_case_string (name, 0), &ct->postcomputes)
+    if (!utf8_strcasecmp (pc->name, name))
+      return pc;
+  return NULL;
+}
+
+static bool
+ctables_parse_pcompute (struct lexer *lexer, struct dictionary *dict,
+                        struct ctables *ct)
+{
+  int pcompute_start = lex_ofs (lexer) - 1;
+
+  if (!lex_match (lexer, T_AND))
+    {
+      lex_error_expecting (lexer, "&");
+      return false;
+    }
+  if (!lex_force_id (lexer))
+    return false;
+
+  char *name = ss_xstrdup (lex_tokss (lexer));
+
+  lex_get (lexer);
+  if (!lex_force_match (lexer, T_EQUALS)
+      || !lex_force_match_id (lexer, "EXPR")
+      || !lex_force_match (lexer, T_LPAREN))
+    {
+      free (name);
+      return false;
+    }
+
+  int expr_start = lex_ofs (lexer);
+  struct ctables_pcexpr *expr = ctables_pcexpr_parse_add (lexer, dict);
+  int expr_end = lex_ofs (lexer) - 1;
+  if (!expr || !lex_force_match (lexer, T_RPAREN))
+    {
+      ctables_pcexpr_destroy (expr);
+      free (name);
+      return false;
+    }
+  int pcompute_end = lex_ofs (lexer) - 1;
+
+  struct msg_location *location = lex_ofs_location (lexer, pcompute_start,
+                                                    pcompute_end);
+
+  struct ctables_postcompute *pc = ctables_find_postcompute (ct, name);
+  if (pc)
+    {
+      msg_at (SW, location, _("New definition of &%s will override the "
+                              "previous definition."),
+              pc->name);
+      msg_at (SN, pc->location, _("This is the previous definition."));
+
+      ctables_pcexpr_destroy (pc->expr);
+      msg_location_destroy (pc->location);
+      free (name);
+    }
+  else
+    {
+      pc = xmalloc (sizeof *pc);
+      *pc = (struct ctables_postcompute) { .name = name };
+      hmap_insert (&ct->postcomputes, &pc->hmap_node,
+                   utf8_hash_case_string (pc->name, 0));
+    }
+  pc->expr = expr;
+  pc->location = location;
+  if (!pc->label)
+    pc->label = lex_ofs_representation (lexer, expr_start, expr_end);
+  return true;
+}
+
+static bool
+ctables_parse_pproperties_format (struct lexer *lexer,
+                                  struct ctables_summary_spec_set *sss)
+{
+  *sss = (struct ctables_summary_spec_set) { .n = 0 };
+
+  while (lex_token (lexer) != T_ENDCMD && lex_token (lexer) != T_SLASH
+         && !(lex_token (lexer) == T_ID
+              && (lex_id_match (ss_cstr ("LABEL"), lex_tokss (lexer))
+                  || lex_id_match (ss_cstr ("HIDESOURCECATS"),
+                                   lex_tokss (lexer)))))
+    {
+      /* Parse function. */
+      enum ctables_summary_function function;
+      enum ctables_weighting weighting;
+      enum ctables_area_type area;
+      if (!parse_ctables_summary_function (lexer, &function, &weighting, &area))
+        goto error;
+
+      /* Parse percentile. */
+      double percentile = 0;
+      if (function == CTSF_PTILE)
+        {
+          if (!lex_force_num_range_closed (lexer, "PTILE", 0, 100))
+            goto error;
+          percentile = lex_number (lexer);
+          lex_get (lexer);
+        }
+
+      /* Parse format. */
+      struct fmt_spec format;
+      bool is_ctables_format;
+      if (!parse_ctables_format_specifier (lexer, &format, &is_ctables_format))
+        goto error;
+
+      if (sss->n >= sss->allocated)
+        sss->specs = x2nrealloc (sss->specs, &sss->allocated,
+                                 sizeof *sss->specs);
+      sss->specs[sss->n++] = (struct ctables_summary_spec) {
+        .function = function,
+        .weighting = weighting,
+        .calc_area = area,
+        .user_area = area,
+        .percentile = percentile,
+        .format = format,
+        .is_ctables_format = is_ctables_format,
+      };
+    }
+  return true;
+
+error:
+  ctables_summary_spec_set_uninit (sss);
+  return false;
+}
+
+static bool
+ctables_parse_pproperties (struct lexer *lexer, struct ctables *ct)
+{
+  struct ctables_postcompute **pcs = NULL;
+  size_t n_pcs = 0;
+  size_t allocated_pcs = 0;
+
+  while (lex_match (lexer, T_AND))
+    {
+      if (!lex_force_id (lexer))
+        goto error;
+      struct ctables_postcompute *pc
+        = ctables_find_postcompute (ct, lex_tokcstr (lexer));
+      if (!pc)
+        {
+          msg (SE, _("Unknown computed category &%s."), lex_tokcstr (lexer));
+          goto error;
+        }
+      lex_get (lexer);
+
+      if (n_pcs >= allocated_pcs)
+        pcs = x2nrealloc (pcs, &allocated_pcs, sizeof *pcs);
+      pcs[n_pcs++] = pc;
+    }
+
+  while (lex_token (lexer) != T_SLASH && lex_token (lexer) != T_ENDCMD)
+    {
+      if (lex_match_id (lexer, "LABEL"))
+        {
+          lex_match (lexer, T_EQUALS);
+          if (!lex_force_string (lexer))
+            goto error;
+
+          for (size_t i = 0; i < n_pcs; i++)
+            {
+              free (pcs[i]->label);
+              pcs[i]->label = ss_xstrdup (lex_tokss (lexer));
+            }
+
+          lex_get (lexer);
+        }
+      else if (lex_match_id (lexer, "FORMAT"))
+        {
+          lex_match (lexer, T_EQUALS);
+
+          struct ctables_summary_spec_set sss;
+          if (!ctables_parse_pproperties_format (lexer, &sss))
+            goto error;
+
+          for (size_t i = 0; i < n_pcs; i++)
+            {
+              if (pcs[i]->specs)
+                ctables_summary_spec_set_uninit (pcs[i]->specs);
+              else
+                pcs[i]->specs = xmalloc (sizeof *pcs[i]->specs);
+              ctables_summary_spec_set_clone (pcs[i]->specs, &sss);
+            }
+          ctables_summary_spec_set_uninit (&sss);
+        }
+      else if (lex_match_id (lexer, "HIDESOURCECATS"))
+        {
+          lex_match (lexer, T_EQUALS);
+          bool hide_source_cats;
+          if (!parse_bool (lexer, &hide_source_cats))
+            goto error;
+          for (size_t i = 0; i < n_pcs; i++)
+            pcs[i]->hide_source_cats = hide_source_cats;
+        }
+      else
+        {
+          lex_error_expecting (lexer, "LABEL", "FORMAT", "HIDESOURCECATS");
+          goto error;
+        }
+    }
+  free (pcs);
+  return true;
+
+error:
+  free (pcs);
+  return false;
+}
+
+static void
+put_strftime (struct string *out, time_t now, const char *format)
+{
+  const struct tm *tm = localtime (&now);
+  char value[128];
+  strftime (value, sizeof value, format, tm);
+  ds_put_cstr (out, value);
+}
+
+static bool
+skip_prefix (struct substring *s, struct substring prefix)
+{
+  if (ss_starts_with (*s, prefix))
+    {
+      ss_advance (s, prefix.length);
+      return true;
+    }
+  else
+    return false;
+}
+
+static void
+put_table_expression (struct string *out, struct lexer *lexer,
+                      struct dictionary *dict, int expr_start, int expr_end)
+{
+  size_t nest = 0;
+  for (int ofs = expr_start; ofs < expr_end; ofs++)
+    {
+      const struct token *t = lex_ofs_token (lexer, ofs);
+      if (t->type == T_LBRACK)
+        nest++;
+      else if (t->type == T_RBRACK && nest > 0)
+        nest--;
+      else if (nest > 0)
+        {
+          /* Nothing. */
+        }
+      else if (t->type == T_ID)
+        {
+          const struct variable *var
+            = dict_lookup_var (dict, t->string.string);
+          const char *label = var ? var_get_label (var) : NULL;
+          ds_put_cstr (out, label ? label : t->string.string);
+        }
+      else
+        {
+          if (ofs != expr_start && t->type != T_RPAREN && ds_last (out) != ' ')
+            ds_put_byte (out, ' ');
+
+          char *repr = lex_ofs_representation (lexer, ofs, ofs);
+          ds_put_cstr (out, repr);
+          free (repr);
+
+          if (ofs + 1 != expr_end && t->type != T_LPAREN)
+            ds_put_byte (out, ' ');
+        }
+    }
+}
+
+static void
+put_title_text (struct string *out, struct substring in, time_t now,
+                struct lexer *lexer, struct dictionary *dict,
+                int expr_start, int expr_end)
+{
+  for (;;)
+    {
+      size_t chunk = ss_find_byte (in, ')');
+      ds_put_substring (out, ss_head (in, chunk));
+      ss_advance (&in, chunk);
+      if (ss_is_empty (in))
+        return;
+
+      if (skip_prefix (&in, ss_cstr (")DATE")))
+        put_strftime (out, now, "%x");
+      else if (skip_prefix (&in, ss_cstr (")TIME")))
+        put_strftime (out, now, "%X");
+      else if (skip_prefix (&in, ss_cstr (")TABLE")))
+        put_table_expression (out, lexer, dict, expr_start, expr_end);
+      else
+        {
+          ds_put_byte (out, ')');
+          ss_advance (&in, 1);
+        }
+    }
+}
+
+int
+cmd_ctables (struct lexer *lexer, struct dataset *ds)
+{
+  struct casereader *input = NULL;
+
+  struct measure_guesser *mg = measure_guesser_create (ds);
+  if (mg)
+    {
+      input = proc_open (ds);
+      measure_guesser_run (mg, input);
+      measure_guesser_destroy (mg);
+    }
+
+  size_t n_vars = dict_get_n_vars (dataset_dict (ds));
+  enum ctables_vlabel *vlabels = xnmalloc (n_vars, sizeof *vlabels);
+  enum settings_value_show tvars = settings_get_show_variables ();
+  for (size_t i = 0; i < n_vars; i++)
+    vlabels[i] = (enum ctables_vlabel) tvars;
+
+  struct pivot_table_look *look = pivot_table_look_unshare (
+    pivot_table_look_ref (pivot_table_look_get_default ()));
+  look->omit_empty = false;
+
+  struct ctables *ct = xmalloc (sizeof *ct);
+  *ct = (struct ctables) {
+    .dict = dataset_dict (ds),
+    .look = look,
+    .ctables_formats = FMT_SETTINGS_INIT,
+    .vlabels = vlabels,
+    .postcomputes = HMAP_INITIALIZER (ct->postcomputes),
+  };
+
+  time_t now = time (NULL);
+
+  struct ctf
+    {
+      enum fmt_type type;
+      const char *dot_string;
+      const char *comma_string;
+    };
+  static const struct ctf ctfs[4] = {
+    { CTEF_NEGPAREN, "(,,,)",   "(...)" },
+    { CTEF_NEQUAL,   "-,N=,,",  "-.N=.." },
+    { CTEF_PAREN,    "-,(,),",  "-.(.)." },
+    { CTEF_PCTPAREN, "-,(,%),", "-.(.%)." },
+  };
+  bool is_dot = settings_get_fmt_settings ()->decimal == '.';
+  for (size_t i = 0; i < 4; i++)
+    {
+      const char *s = is_dot ? ctfs[i].dot_string : ctfs[i].comma_string;
+      fmt_settings_set_cc (&ct->ctables_formats, ctfs[i].type,
+                           fmt_number_style_from_string (s));
+    }
+
+  if (!lex_force_match (lexer, T_SLASH))
+    goto error;
+
+  while (!lex_match_id (lexer, "TABLE"))
+    {
+      if (lex_match_id (lexer, "FORMAT"))
+        {
+          double widths[2] = { SYSMIS, SYSMIS };
+          double units_per_inch = 72.0;
+
+          while (lex_token (lexer) != T_SLASH)
+            {
+              if (lex_match_id (lexer, "MINCOLWIDTH"))
+                {
+                  if (!parse_col_width (lexer, "MINCOLWIDTH", &widths[0]))
+                    goto error;
+                }
+              else if (lex_match_id (lexer, "MAXCOLWIDTH"))
+                {
+                  if (!parse_col_width (lexer, "MAXCOLWIDTH", &widths[1]))
+                    goto error;
+                }
+              else if (lex_match_id (lexer, "UNITS"))
+                {
+                  lex_match (lexer, T_EQUALS);
+                  if (lex_match_id (lexer, "POINTS"))
+                    units_per_inch = 72.0;
+                  else if (lex_match_id (lexer, "INCHES"))
+                    units_per_inch = 1.0;
+                  else if (lex_match_id (lexer, "CM"))
+                    units_per_inch = 2.54;
+                  else
+                    {
+                      lex_error_expecting (lexer, "POINTS", "INCHES", "CM");
+                      goto error;
+                    }
+                }
+              else if (lex_match_id (lexer, "EMPTY"))
+                {
+                  free (ct->zero);
+                  ct->zero = NULL;
+
+                  lex_match (lexer, T_EQUALS);
+                  if (lex_match_id (lexer, "ZERO"))
+                    {
+                      /* Nothing to do. */
+                    }
+                  else if (lex_match_id (lexer, "BLANK"))
+                    ct->zero = xstrdup ("");
+                  else if (lex_force_string (lexer))
+                    {
+                      ct->zero = ss_xstrdup (lex_tokss (lexer));
+                      lex_get (lexer);
+                    }
+                  else
+                    goto error;
+                }
+              else if (lex_match_id (lexer, "MISSING"))
+                {
+                  lex_match (lexer, T_EQUALS);
+                  if (!lex_force_string (lexer))
+                    goto error;
+
+                  free (ct->missing);
+                  ct->missing = (strcmp (lex_tokcstr (lexer), ".")
+                                 ? ss_xstrdup (lex_tokss (lexer))
+                                 : NULL);
+                  lex_get (lexer);
+                }
+              else
+                {
+                  lex_error_expecting (lexer, "MINCOLWIDTH", "MAXCOLWIDTH",
+                                       "UNITS", "EMPTY", "MISSING");
+                  goto error;
+                }
+            }
+
+          if (widths[0] != SYSMIS && widths[1] != SYSMIS
+              && widths[0] > widths[1])
+            {
+              msg (SE, _("MINCOLWIDTH must not be greater than MAXCOLWIDTH."));
+              goto error;
+            }
+
+          for (size_t i = 0; i < 2; i++)
+            if (widths[i] != SYSMIS)
+              {
+                int *wr = ct->look->width_ranges[TABLE_HORZ];
+                wr[i] = widths[i] / units_per_inch * 96.0;
+                if (wr[0] > wr[1])
+                  wr[!i] = wr[i];
+              }
+        }
+      else if (lex_match_id (lexer, "VLABELS"))
+        {
+          if (!lex_force_match_id (lexer, "VARIABLES"))
+            goto error;
+          lex_match (lexer, T_EQUALS);
+
+          struct variable **vars;
+          size_t n_vars;
+          if (!parse_variables (lexer, dataset_dict (ds), &vars, &n_vars,
+                                PV_NO_SCRATCH))
+            goto error;
+
+          if (!lex_force_match_id (lexer, "DISPLAY"))
+            {
+              free (vars);
+              goto error;
+            }
+          lex_match (lexer, T_EQUALS);
+
+          enum ctables_vlabel vlabel;
+          if (lex_match_id (lexer, "DEFAULT"))
+            vlabel = (enum ctables_vlabel) settings_get_show_variables ();
+          else if (lex_match_id (lexer, "NAME"))
+            vlabel = CTVL_NAME;
+          else if (lex_match_id (lexer, "LABEL"))
+            vlabel = CTVL_LABEL;
+          else if (lex_match_id (lexer, "BOTH"))
+            vlabel = CTVL_BOTH;
+          else if (lex_match_id (lexer, "NONE"))
+            vlabel = CTVL_NONE;
+          else
+            {
+              lex_error_expecting (lexer, "DEFAULT", "NAME", "LABEL",
+                                   "BOTH", "NONE");
+              free (vars);
+              goto error;
+            }
+
+          for (size_t i = 0; i < n_vars; i++)
+            ct->vlabels[var_get_dict_index (vars[i])] = vlabel;
+          free (vars);
+        }
+      else if (lex_match_id (lexer, "MRSETS"))
+        {
+          if (!lex_force_match_id (lexer, "COUNTDUPLICATES"))
+            goto error;
+          lex_match (lexer, T_EQUALS);
+          if (!parse_bool (lexer, &ct->mrsets_count_duplicates))
+            goto error;
+        }
+      else if (lex_match_id (lexer, "SMISSING"))
+        {
+          if (lex_match_id (lexer, "VARIABLE"))
+            ct->smissing_listwise = false;
+          else if (lex_match_id (lexer, "LISTWISE"))
+            ct->smissing_listwise = true;
+          else
+            {
+              lex_error_expecting (lexer, "VARIABLE", "LISTWISE");
+              goto error;
+            }
+        }
+      else if (lex_match_id (lexer, "PCOMPUTE"))
+        {
+          if (!ctables_parse_pcompute (lexer, dataset_dict (ds), ct))
+            goto error;
+        }
+      else if (lex_match_id (lexer, "PPROPERTIES"))
+        {
+          if (!ctables_parse_pproperties (lexer, ct))
+            goto error;
+        }
+      else if (lex_match_id (lexer, "WEIGHT"))
+        {
+          if (!lex_force_match_id (lexer, "VARIABLE"))
+            goto error;
+          lex_match (lexer, T_EQUALS);
+          ct->e_weight = parse_variable (lexer, dataset_dict (ds));
+          if (!ct->e_weight)
+            goto error;
+        }
+      else if (lex_match_id (lexer, "HIDESMALLCOUNTS"))
+        {
+          if (lex_match_id (lexer, "COUNT"))
+            {
+              lex_match (lexer, T_EQUALS);
+              if (!lex_force_int_range (lexer, "HIDESMALLCOUNTS COUNT",
+                                        2, INT_MAX))
+                goto error;
+              ct->hide_threshold = lex_integer (lexer);
+              lex_get (lexer);
+            }
+          else if (ct->hide_threshold == 0)
+            ct->hide_threshold = 5;
+        }
+      else
+        {
+          lex_error_expecting (lexer, "FORMAT", "VLABELS", "MRSETS",
+                               "SMISSING", "PCOMPUTE", "PPROPERTIES",
+                               "WEIGHT", "HIDESMALLCOUNTS", "TABLE");
+          goto error;
+        }
+
+      if (!lex_force_match (lexer, T_SLASH))
+        goto error;
+    }
+
+  size_t allocated_tables = 0;
+  do
+    {
+      if (ct->n_tables >= allocated_tables)
+        ct->tables = x2nrealloc (ct->tables, &allocated_tables,
+                                 sizeof *ct->tables);
+
+      struct ctables_category *cat = xmalloc (sizeof *cat);
+      *cat = (struct ctables_category) {
+        .type = CCT_VALUE,
+        .include_missing = false,
+        .sort_ascending = true,
+      };
+
+      struct ctables_categories *c = xmalloc (sizeof *c);
+      size_t n_vars = dict_get_n_vars (dataset_dict (ds));
+      *c = (struct ctables_categories) {
+        .n_refs = n_vars,
+        .cats = cat,
+        .n_cats = 1,
+        .show_empty = true,
+      };
+
+      struct ctables_categories **categories = xnmalloc (n_vars,
+                                                         sizeof *categories);
+      for (size_t i = 0; i < n_vars; i++)
+        categories[i] = c;
+
+      struct ctables_table *t = xmalloc (sizeof *t);
+      *t = (struct ctables_table) {
+        .ctables = ct,
+        .slabels_axis = PIVOT_AXIS_COLUMN,
+        .slabels_visible = true,
+        .clabels_values_map = HMAP_INITIALIZER (t->clabels_values_map),
+        .label_axis = {
+          [PIVOT_AXIS_ROW] = PIVOT_AXIS_ROW,
+          [PIVOT_AXIS_COLUMN] = PIVOT_AXIS_COLUMN,
+          [PIVOT_AXIS_LAYER] = PIVOT_AXIS_LAYER,
+        },
+        .clabels_from_axis = PIVOT_AXIS_LAYER,
+        .clabels_to_axis = PIVOT_AXIS_LAYER,
+        .categories = categories,
+        .n_categories = n_vars,
+        .cilevel = 95,
+      };
+      ct->tables[ct->n_tables++] = t;
+
+      lex_match (lexer, T_EQUALS);
+      int expr_start = lex_ofs (lexer);
+      if (!ctables_axis_parse (lexer, dataset_dict (ds),
+                               &t->axes[PIVOT_AXIS_ROW]))
+        goto error;
+      if (lex_match (lexer, T_BY))
+        {
+          if (!ctables_axis_parse (lexer, dataset_dict (ds),
+                                   &t->axes[PIVOT_AXIS_COLUMN]))
+            goto error;
+
+          if (lex_match (lexer, T_BY))
+            {
+              if (!ctables_axis_parse (lexer, dataset_dict (ds),
+                                       &t->axes[PIVOT_AXIS_LAYER]))
+                goto error;
+            }
+        }
+      int expr_end = lex_ofs (lexer);
+
+      if (!t->axes[PIVOT_AXIS_ROW] && !t->axes[PIVOT_AXIS_COLUMN]
+          && !t->axes[PIVOT_AXIS_LAYER])
+        {
+          lex_error (lexer, _("At least one variable must be specified."));
+          goto error;
+        }
+
+      const struct ctables_axis *scales[PIVOT_N_AXES];
+      size_t n_scales = 0;
+      for (enum pivot_axis_type a = 0; a < PIVOT_N_AXES; a++)
+        {
+          scales[a] = find_scale (t->axes[a]);
+          if (scales[a])
+            n_scales++;
+        }
+      if (n_scales > 1)
+        {
+          msg (SE, _("Scale variables may appear only on one axis."));
+          if (scales[PIVOT_AXIS_ROW])
+            msg_at (SN, scales[PIVOT_AXIS_ROW]->loc,
+                    _("This scale variable appears on the rows axis."));
+          if (scales[PIVOT_AXIS_COLUMN])
+            msg_at (SN, scales[PIVOT_AXIS_COLUMN]->loc,
+                    _("This scale variable appears on the columns axis."));
+          if (scales[PIVOT_AXIS_LAYER])
+            msg_at (SN, scales[PIVOT_AXIS_LAYER]->loc,
+                    _("This scale variable appears on the layer axis."));
+          goto error;
+        }
+
+      const struct ctables_axis *summaries[PIVOT_N_AXES];
+      size_t n_summaries = 0;
+      for (enum pivot_axis_type a = 0; a < PIVOT_N_AXES; a++)
+        {
+          summaries[a] = (scales[a]
+                          ? scales[a]
+                          : find_categorical_summary_spec (t->axes[a]));
+          if (summaries[a])
+            n_summaries++;
+        }
+      if (n_summaries > 1)
+        {
+          msg (SE, _("Summaries may appear only on one axis."));
+          for (enum pivot_axis_type a = 0; a < PIVOT_N_AXES; a++)
+            if (summaries[a])
+              {
+                msg_at (SN, summaries[a]->loc,
+                        a == PIVOT_AXIS_ROW
+                        ? _("This variable on the rows axis has a summary.")
+                        : a == PIVOT_AXIS_COLUMN
+                        ? _("This variable on the columns axis has a summary.")
+                        : _("This variable on the layers axis has a summary."));
+                if (scales[a])
+                  msg_at (SN, summaries[a]->loc,
+                          _("This is a scale variable, so it always has a "
+                            "summary even if the syntax does not explicitly "
+                            "specify one."));
+              }
+          goto error;
+        }
+      for (enum pivot_axis_type a = 0; a < PIVOT_N_AXES; a++)
+        if (n_summaries ? summaries[a] : t->axes[a])
+          {
+            t->summary_axis = a;
+            break;
+          }
+
+      if (lex_token (lexer) == T_ENDCMD)
+        {
+          if (!ctables_prepare_table (t))
+            goto error;
+          break;
+        }
+      if (!lex_force_match (lexer, T_SLASH))
+        goto error;
+
+      while (!lex_match_id (lexer, "TABLE") && lex_token (lexer) != T_ENDCMD)
+        {
+          if (lex_match_id (lexer, "SLABELS"))
+            {
+              while (lex_token (lexer) != T_SLASH && lex_token (lexer) != T_ENDCMD)
+                {
+                  if (lex_match_id (lexer, "POSITION"))
+                    {
+                      lex_match (lexer, T_EQUALS);
+                      if (lex_match_id (lexer, "COLUMN"))
+                        t->slabels_axis = PIVOT_AXIS_COLUMN;
+                      else if (lex_match_id (lexer, "ROW"))
+                        t->slabels_axis = PIVOT_AXIS_ROW;
+                      else if (lex_match_id (lexer, "LAYER"))
+                        t->slabels_axis = PIVOT_AXIS_LAYER;
+                      else
+                        {
+                          lex_error_expecting (lexer, "COLUMN", "ROW", "LAYER");
+                          goto error;
+                        }
+                    }
+                  else if (lex_match_id (lexer, "VISIBLE"))
+                    {
+                      lex_match (lexer, T_EQUALS);
+                      if (!parse_bool (lexer, &t->slabels_visible))
+                        goto error;
+                    }
+                  else
+                    {
+                      lex_error_expecting (lexer, "POSITION", "VISIBLE");
+                      goto error;
+                    }
+                }
+            }
+          else if (lex_match_id (lexer, "CLABELS"))
+            {
+              if (lex_match_id (lexer, "AUTO"))
+                {
+                  t->label_axis[PIVOT_AXIS_ROW] = PIVOT_AXIS_ROW;
+                  t->label_axis[PIVOT_AXIS_COLUMN] = PIVOT_AXIS_COLUMN;
+                }
+              else if (lex_match_id (lexer, "ROWLABELS"))
+                {
+                  lex_match (lexer, T_EQUALS);
+                  if (lex_match_id (lexer, "OPPOSITE"))
+                    t->label_axis[PIVOT_AXIS_ROW] = PIVOT_AXIS_COLUMN;
+                  else if (lex_match_id (lexer, "LAYER"))
+                    t->label_axis[PIVOT_AXIS_ROW] = PIVOT_AXIS_LAYER;
+                  else
+                    {
+                      lex_error_expecting (lexer, "OPPOSITE", "LAYER");
+                      goto error;
+                    }
+                }
+              else if (lex_match_id (lexer, "COLLABELS"))
+                {
+                  lex_match (lexer, T_EQUALS);
+                  if (lex_match_id (lexer, "OPPOSITE"))
+                    t->label_axis[PIVOT_AXIS_COLUMN] = PIVOT_AXIS_ROW;
+                  else if (lex_match_id (lexer, "LAYER"))
+                    t->label_axis[PIVOT_AXIS_COLUMN] = PIVOT_AXIS_LAYER;
+                  else
+                    {
+                      lex_error_expecting (lexer, "OPPOSITE", "LAYER");
+                      goto error;
+                    }
+                }
+              else
+                {
+                  lex_error_expecting (lexer, "AUTO", "ROWLABELS",
+                                       "COLLABELS");
+                  goto error;
+                }
+            }
+          else if (lex_match_id (lexer, "CRITERIA"))
+            {
+              if (!lex_force_match_id (lexer, "CILEVEL"))
+                goto error;
+              lex_match (lexer, T_EQUALS);
+
+              if (!lex_force_num_range_halfopen (lexer, "CILEVEL", 0, 100))
+                goto error;
+              t->cilevel = lex_number (lexer);
+              lex_get (lexer);
+            }
+          else if (lex_match_id (lexer, "CATEGORIES"))
+            {
+              if (!ctables_table_parse_categories (lexer, dataset_dict (ds),
+                                                   ct, t))
+                goto error;
+            }
+          else if (lex_match_id (lexer, "TITLES"))
+            {
+              do
+                {
+                  char **textp;
+                  if (lex_match_id (lexer, "CAPTION"))
+                    textp = &t->caption;
+                  else if (lex_match_id (lexer, "CORNER"))
+                    textp = &t->corner;
+                  else if (lex_match_id (lexer, "TITLE"))
+                    textp = &t->title;
+                  else
+                    {
+                      lex_error_expecting (lexer, "CAPTION", "CORNER", "TITLE");
+                      goto error;
+                    }
+                  lex_match (lexer, T_EQUALS);
+
+                  struct string s = DS_EMPTY_INITIALIZER;
+                  while (lex_is_string (lexer))
+                    {
+                      if (!ds_is_empty (&s))
+                        ds_put_byte (&s, ' ');
+                      put_title_text (&s, lex_tokss (lexer), now,
+                                      lexer, dataset_dict (ds),
+                                      expr_start, expr_end);
+                      lex_get (lexer);
+                    }
+                  free (*textp);
+                  *textp = ds_steal_cstr (&s);
+                }
+              while (lex_token (lexer) != T_SLASH
+                     && lex_token (lexer) != T_ENDCMD);
+            }
+          else if (lex_match_id (lexer, "SIGTEST"))
+            {
+              int start_ofs = lex_ofs (lexer) - 1;
+              if (!t->chisq)
+                {
+                  t->chisq = xmalloc (sizeof *t->chisq);
+                  *t->chisq = (struct ctables_chisq) {
+                    .alpha = .05,
+                    .include_mrsets = true,
+                    .all_visible = true,
+                  };
+                }
+
+              do
+                {
+                  if (lex_match_id (lexer, "TYPE"))
+                    {
+                      lex_match (lexer, T_EQUALS);
+                      if (!lex_force_match_id (lexer, "CHISQUARE"))
+                        goto error;
+                    }
+                  else if (lex_match_id (lexer, "ALPHA"))
+                    {
+                      lex_match (lexer, T_EQUALS);
+                      if (!lex_force_num_range_halfopen (lexer, "ALPHA", 0, 1))
+                        goto error;
+                      t->chisq->alpha = lex_number (lexer);
+                      lex_get (lexer);
+                    }
+                  else if (lex_match_id (lexer, "INCLUDEMRSETS"))
+                    {
+                      lex_match (lexer, T_EQUALS);
+                      if (!parse_bool (lexer, &t->chisq->include_mrsets))
+                        goto error;
+                    }
+                  else if (lex_match_id (lexer, "CATEGORIES"))
+                    {
+                      lex_match (lexer, T_EQUALS);
+                      if (lex_match_id (lexer, "ALLVISIBLE"))
+                        t->chisq->all_visible = true;
+                      else if (lex_match_id (lexer, "SUBTOTALS"))
+                        t->chisq->all_visible = false;
+                      else
+                        {
+                          lex_error_expecting (lexer,
+                                               "ALLVISIBLE", "SUBTOTALS");
+                          goto error;
+                        }
+                    }
+                  else
+                    {
+                      lex_error_expecting (lexer, "TYPE", "ALPHA",
+                                           "INCLUDEMRSETS", "CATEGORIES");
+                      goto error;
+                    }
+                }
+              while (lex_token (lexer) != T_SLASH
+                     && lex_token (lexer) != T_ENDCMD);
+
+              lex_ofs_error (lexer, start_ofs, lex_ofs (lexer) - 1,
+                             _("Support for SIGTEST not yet implemented."));
+              goto error;
+            }
+          else if (lex_match_id (lexer, "COMPARETEST"))
+            {
+              int start_ofs = lex_ofs (lexer);
+              if (!t->pairwise)
+                {
+                  t->pairwise = xmalloc (sizeof *t->pairwise);
+                  *t->pairwise = (struct ctables_pairwise) {
+                    .type = PROP,
+                    .alpha = { .05, .05 },
+                    .adjust = BONFERRONI,
+                    .include_mrsets = true,
+                    .meansvariance_allcats = true,
+                    .all_visible = true,
+                    .merge = false,
+                    .apa_style = true,
+                    .show_sig = false,
+                  };
+                }
+
+              do
+                {
+                  if (lex_match_id (lexer, "TYPE"))
+                    {
+                      lex_match (lexer, T_EQUALS);
+                      if (lex_match_id (lexer, "PROP"))
+                        t->pairwise->type = PROP;
+                      else if (lex_match_id (lexer, "MEAN"))
+                        t->pairwise->type = MEAN;
+                      else
+                        {
+                          lex_error_expecting (lexer, "PROP", "MEAN");
+                          goto error;
+                        }
+                    }
+                  else if (lex_match_id (lexer, "ALPHA"))
+                    {
+                      lex_match (lexer, T_EQUALS);
+
+                      if (!lex_force_num_range_open (lexer, "ALPHA", 0, 1))
+                        goto error;
+                      double a0 = lex_number (lexer);
+                      lex_get (lexer);
+
+                      lex_match (lexer, T_COMMA);
+                      if (lex_is_number (lexer))
+                        {
+                          if (!lex_force_num_range_open (lexer, "ALPHA", 0, 1))
+                            goto error;
+                          double a1 = lex_number (lexer);
+                          lex_get (lexer);
+
+                          t->pairwise->alpha[0] = MIN (a0, a1);
+                          t->pairwise->alpha[1] = MAX (a0, a1);
+                        }
+                      else
+                        t->pairwise->alpha[0] = t->pairwise->alpha[1] = a0;
+                    }
+                  else if (lex_match_id (lexer, "ADJUST"))
+                    {
+                      lex_match (lexer, T_EQUALS);
+                      if (lex_match_id (lexer, "BONFERRONI"))
+                        t->pairwise->adjust = BONFERRONI;
+                      else if (lex_match_id (lexer, "BH"))
+                        t->pairwise->adjust = BH;
+                      else if (lex_match_id (lexer, "NONE"))
+                        t->pairwise->adjust = 0;
+                      else
+                        {
+                          lex_error_expecting (lexer, "BONFERRONI", "BH",
+                                               "NONE");
+                          goto error;
+                        }
+                    }
+                  else if (lex_match_id (lexer, "INCLUDEMRSETS"))
+                    {
+                      lex_match (lexer, T_EQUALS);
+                      if (!parse_bool (lexer, &t->pairwise->include_mrsets))
+                        goto error;
+                    }
+                  else if (lex_match_id (lexer, "MEANSVARIANCE"))
+                    {
+                      lex_match (lexer, T_EQUALS);
+                      if (lex_match_id (lexer, "ALLCATS"))
+                        t->pairwise->meansvariance_allcats = true;
+                      else if (lex_match_id (lexer, "TESTEDCATS"))
+                        t->pairwise->meansvariance_allcats = false;
+                      else
+                        {
+                          lex_error_expecting (lexer, "ALLCATS", "TESTEDCATS");
+                          goto error;
+                        }
+                    }
+                  else if (lex_match_id (lexer, "CATEGORIES"))
+                    {
+                      lex_match (lexer, T_EQUALS);
+                      if (lex_match_id (lexer, "ALLVISIBLE"))
+                        t->pairwise->all_visible = true;
+                      else if (lex_match_id (lexer, "SUBTOTALS"))
+                        t->pairwise->all_visible = false;
+                      else
+                        {
+                          lex_error_expecting (lexer, "ALLVISIBLE",
+                                               "SUBTOTALS");
+                          goto error;
+                        }
+                    }
+                  else if (lex_match_id (lexer, "MERGE"))
+                    {
+                      lex_match (lexer, T_EQUALS);
+                      if (!parse_bool (lexer, &t->pairwise->merge))
+                        goto error;
+                    }
+                  else if (lex_match_id (lexer, "STYLE"))
+                    {
+                      lex_match (lexer, T_EQUALS);
+                      if (lex_match_id (lexer, "APA"))
+                        t->pairwise->apa_style = true;
+                      else if (lex_match_id (lexer, "SIMPLE"))
+                        t->pairwise->apa_style = false;
+                      else
+                        {
+                          lex_error_expecting (lexer, "APA", "SIMPLE");
+                          goto error;
+                        }
+                    }
+                  else if (lex_match_id (lexer, "SHOWSIG"))
+                    {
+                      lex_match (lexer, T_EQUALS);
+                      if (!parse_bool (lexer, &t->pairwise->show_sig))
+                        goto error;
+                    }
+                  else
+                    {
+                      lex_error_expecting (lexer, "TYPE", "ALPHA", "ADJUST",
+                                           "INCLUDEMRSETS", "MEANSVARIANCE",
+                                           "CATEGORIES", "MERGE", "STYLE",
+                                           "SHOWSIG");
+                      goto error;
+                    }
+                }
+              while (lex_token (lexer) != T_SLASH
+                     && lex_token (lexer) != T_ENDCMD);
+
+              lex_ofs_error (lexer, start_ofs, lex_ofs (lexer) - 1,
+                             _("Support for COMPARETEST not yet implemented."));
+              goto error;
+            }
+          else
+            {
+              lex_error_expecting (lexer, "TABLE", "SLABELS", "CLABELS",
+                                   "CRITERIA", "CATEGORIES", "TITLES",
+                                   "SIGTEST", "COMPARETEST");
+              goto error;
+            }
+
+          if (!lex_match (lexer, T_SLASH))
+            break;
+        }
+
+      if (t->label_axis[PIVOT_AXIS_ROW] != PIVOT_AXIS_ROW)
+        {
+          t->clabels_from_axis = PIVOT_AXIS_ROW;
+          if (t->label_axis[PIVOT_AXIS_COLUMN] != PIVOT_AXIS_COLUMN)
+            {
+              msg (SE, _("ROWLABELS and COLLABELS may not both be specified."));
+              goto error;
+            }
+        }
+      else if (t->label_axis[PIVOT_AXIS_COLUMN] != PIVOT_AXIS_COLUMN)
+        t->clabels_from_axis = PIVOT_AXIS_COLUMN;
+      t->clabels_to_axis = t->label_axis[t->clabels_from_axis];
+
+      if (!ctables_prepare_table (t))
+        goto error;
+    }
+  while (lex_token (lexer) != T_ENDCMD);
+
+  if (!input)
+    input = proc_open (ds);
+  bool ok = ctables_execute (ds, input, ct);
+  ok = proc_commit (ds) && ok;
+
+  ctables_destroy (ct);
+  return ok ? CMD_SUCCESS : CMD_FAILURE;
+
+error:
+  if (input)
+    proc_commit (ds);
+  ctables_destroy (ct);
+  return CMD_FAILURE;
+}
+