spv: Encode and decode AHEX format in light binary members.

[pspp] / doc / dev / spv-file-format.texi

@c PSPP - a program for statistical analysis.
@c Copyright (C) 2019 Free Software Foundation, Inc.
@c Permission is granted to copy, distribute and/or modify this document
@c under the terms of the GNU Free Documentation License, Version 1.3
@c or any later version published by the Free Software Foundation;
@c with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts.
@c A copy of the license is included in the section entitled "GNU
@c Free Documentation License".
@c

@node SPSS Viewer File Format
@appendix SPSS Viewer File Format

SPSS Viewer or @file{.spv} files, here called SPV files, are written
by SPSS 16 and later to represent the contents of its output editor.
This chapter documents the format, based on examination of a corpus of
about 8,000 files from a variety of sources.  This description is
detailed enough to both read and write SPV files.

SPSS 15 and earlier versions instead use @file{.spo} files, which have
a completely different output format based on the Microsoft Compound
Document Format.  This format is not documented here.

An SPV file is a Zip archive that can be read with @command{zipinfo}
and @command{unzip} and similar programs.  The final member in the Zip
archive is the @dfn{manifest}, a file named
@file{META-INF/MANIFEST.MF}.  This structure makes SPV files resemble
Java ``JAR'' files (and ODF files), but whereas a JAR manifest
contains a sequence of colon-delimited key/value pairs, an SPV
manifest contains the string @samp{allowPivoting=true}, without a
new-line.  PSPP uses this string to identify an SPV file; it is
invariant across the corpus.@footnote{SPV files always begin with the
7-byte sequence 50 4b 03 04 14 00 08, but this is not a useful magic
number because most Zip archives start the same way.}@footnote{SPSS
writes @file{META-INF/MANIFEST.MF} to every SPV file, but it does not
read it or even require it to exist, so using different contents,
e.g.@: as @samp{allowingPivot=false} has no effect.}

The rest of the members in an SPV file's Zip archive fall into two
categories: @dfn{structure} and @dfn{detail} members.  Structure
member names begin with @file{outputViewer@var{nnnnnnnnnn}}, where
each @var{n} is a decimal digit, and end with @file{.xml}, and often
include the string @file{_heading} in between.  Each of these members
represents some kind of output item (a table, a heading, a block of
text, etc.) or a group of them.  The member whose output goes at the
beginning of the document is numbered 0, the next member in the output
is numbered 1, and so on.

Structure members contain XML.  This XML is sometimes self-contained,
but it often references detail members in the Zip archive, which are
named as follows:

@table @asis
@item @file{@var{prefix}_table.xml} and @file{@var{prefix}_tableData.bin}
@itemx @file{@var{prefix}_lightTableData.bin}
The structure of a table plus its data.  Older SPV files pair a
@file{@var{prefix}_table.xml} file that describes the table's
structure with a binary @file{@var{prefix}_tableData.bin} file that
gives its data.  Newer SPV files (the majority of those in the corpus)
instead include a single @file{@var{prefix}_lightTableData.bin} file
that incorporates both into a single binary format.

@item @file{@var{prefix}_warning.xml} and @file{@var{prefix}_warningData.bin}
@itemx @file{@var{prefix}_lightWarningData.bin}
Same format used for tables, with a different name.

@item @file{@var{prefix}_notes.xml} and @file{@var{prefix}_notesData.bin}
@itemx @file{@var{prefix}_lightNotesData.bin}
Same format used for tables, with a different name.

@item @file{@var{prefix}_chartData.bin} and @file{@var{prefix}_chart.xml}
The structure of a chart plus its data.  Charts do not have a
``light'' format.

@item @file{@var{prefix}_pmml.scf}
@itemx @file{@var{prefix}_stats.scf}
@item @file{@var{prefix}_model.xml}
Not yet investigated.  The corpus contains few examples.
@end table

The @file{@var{prefix}} in the names of the detail members is
typically an 11-digit decimal number that increases for each item,
tending to skip values.  Older SPV files use different naming
conventions.  Structure member refer to detail members by name, and so
their exact names do not matter to readers as long as they are unique.

SPSS tolerates corrupted Zip archives that Zip reader libraries tend
to reject.  These can be fixed up with @command{zip -FF}.

@menu
* SPV Structure Member Format::
* SPV Light Detail Member Format::
* SPV Legacy Detail Member Binary Format::
* SPV Legacy Detail Member XML Format::
@end menu

@node SPV Structure Member Format
@section Structure Member Format

A structure member lays out the high-level structure for a group of
output items such as heading, tables, and charts.  Structure members
do not include the details of tables and charts but instead refer to
them by their member names.

Structure members' XML files claim conformance with a collection of
XML Schemas.  These schemas are distributed, under a nonfree license,
with SPSS binaries.  Fortunately, the schemas are not necessary to
understand the structure members.  The schemas can even
be deceptive because they document elements and attributes that are
not in the corpus and do not document elements and attributes that are
commonly found in the corpus.

Structure members use a different XML namespace for each schema, but
these namespaces are not entirely consistent.  In some SPV files, for
example, the @code{viewer-tree} schema is associated with namespace
@indicateurl{http://xml.spss.com/spss/viewer-tree} and in others with
@indicateurl{http://xml.spss.com/spss/viewer/viewer-tree} (note the
additional @file{viewer/}).  Under either name, the schema URIs are
not resolvable to obtain the schemas themselves.

One may ignore all of the above in interpreting a structure member.
The actual XML has a simple and straightforward form that does not
require a reader to take schemas or namespaces into account.  A
structure member's root is @code{heading} element, which contains
@code{heading} or @code{container} elements (or a mix), forming a
tree.  In turn, @code{container} holds a @code{label} and one more
child, usually @code{text} or @code{table}.

The following sections document the elements found in structure
members in a context-free grammar-like fashion.  Consider the
following example, which specifies the attributes and content for the
@code{container} element:

@example
container
   :visibility=(visible | hidden)
   :page-break-before=(always)?
   :text-align=(left | center)?
   :width=dimension
=> label (table | container_text | graph | model | object | image | tree)
@end example

Each attribute specification begins with @samp{:} followed by the
attribute's name.  If the attribute's value has an easily specified
form, then @samp{=} and its description follows the name.  Finally, if
the attribute is optional, the specification ends with @samp{?}.  The
following value specifications are defined:

@table @code
@item (@var{a} | @var{b} | @dots{})
One of the listed literal strings.  If only one string is listed, it
is the only acceptable value.  If @code{OTHER} is listed, then any
string not explicitly listed is also accepted.

@item bool
Either @code{true} or @code{false}.

@item dimension
A floating-point number followed by a unit, e.g.@: @code{10pt}.  Units
in the corpus include @code{in} (inch), @code{pt} (points, 72/inch),
@code{px} (``device-independent pixels'', 96/inch), and @code{cm}.  If
the unit is omitted then points should be assumed.  The number and
unit may be separated by white space.

The corpus also includes localized names for units.  A reader must
understand these to properly interpret the dimension:

@table @asis
@item inch
@code{인치}, @code{pol.}, @code{cala}, @code{cali}

@item point
@code{пт}

@item centimeter
@code{см}
@end table

@item real
A floating-point number.

@item int
An integer.

@item color
A color in one of the forms @code{#@var{rr}@var{gg}@var{bb}} or
@code{@var{rr}@var{gg}@var{bb}}, or the string @code{transparent}, or
one of the standard Web color names.

@item ref
@item ref @var{element}
@itemx ref(@var{elem1} | @var{elem2} | @dots{})
The name from the @code{id} attribute in some element.  If one or more
elements are named, the name must refer to one of those elements,
otherwise any element is acceptable.
@end table

All elements have an optional @code{id} attribute.  If present, its
value must be unique.  In practice many elements are assigned
@code{id} attributes that are never referenced.

The content specification for an element supports the following
syntax:

@table @code
@item @var{element}
An element.

@item @var{a} @var{b}
@var{a} followed by @var{b}.

@item @var{a} | @var{b} | @var{c}
One of @var{a} or @var{b} or @var{c}.

@item @var{a}?
Zero or one instances of @var{a}.

@item @var{a}*
Zero or more instances of @var{a}.

@item @var{b}+
One or more instances of @var{a}.

@item (@var{subexpression})
Grouping for a subexpression.

@item EMPTY
No content.

@item TEXT
Text and CDATA.
@end table

Element and attribute names are sometimes suffixed by another name in
square brackets to distinguish different uses of the same name.  For
example, structure XML has two @code{text} elements, one inside
@code{container}, the other inside @code{pageParagraph}.  The former
is defined as @code{text[container_text]} and referenced as
@code{container_text}, the latter defined as
@code{text[pageParagraph_text]} and referenced as
@code{pageParagraph_text}.

This language is used in the PSPP source code for parsing structure
and detail XML members.  Refer to
@file{src/output/spv/structure-xml.grammar} and
@file{src/output/spv/detail-xml.grammar} for the full grammars.

The following example shows the contents of a typical structure member
for a @cmd{DESCRIPTIVES} procedure.  A real structure member is not
indented.  This example also omits most attributes, all XML namespace
information, and the CSS from the embedded HTML:

@example
<?xml version="1.0" encoding="utf-8"?>
<heading>
  <label>Output</label>
  <heading commandName="Descriptives">
    <label>Descriptives</label>
    <container>
      <label>Title</label>
      <text commandName="Descriptives" type="title">
        <html lang="en">
<![CDATA[<head><style type="text/css">...</style></head><BR>Descriptives]]>
        </html>
      </text>
    </container>
    <container visibility="hidden">
      <label>Notes</label>
      <table commandName="Descriptives" subType="Notes" type="note">
        <tableStructure>
          <dataPath>00000000001_lightNotesData.bin</dataPath>
        </tableStructure>
      </table>
    </container>
    <container>
      <label>Descriptive Statistics</label>
      <table commandName="Descriptives" subType="Descriptive Statistics"
             type="table">
        <tableStructure>
          <dataPath>00000000002_lightTableData.bin</dataPath>
        </tableStructure>
      </table>
    </container>
  </heading>
</heading>
@end example

@menu
* SPV Structure heading Element::
* SPV Structure label Element::
* SPV Structure container Element::
* SPV Structure text Element (Inside @code{container})::
* SPV Structure html Element::
* SPV Structure table Element::
* SPV Structure graph Element::
* SPV Structure model Element::
* SPV Structure tree Element::
* SPV Structure Path Elements::
* SPV Structure pageSetup Element::
* SPV Structure @code{text} Element (Inside @code{pageParagraph})::
@end menu

@node SPV Structure heading Element
@subsection The @code{heading} Element

@example
heading[root_heading]
   :creator-version?
   :creator?
   :creation-date-time?
   :lockReader=bool?
   :schemaLocation?
=> label pageSetup? (container | heading)*

heading
   :creator-version?
   :commandName?
   :visibility[heading_visibility]=(collapsed)?
   :locale?
   :olang?
=> label (container | heading)*
@end example

The root of a structure member is a @code{heading}, which represents a
section of output beginning with a @code{label} and
ordinarily followed by content containers or further nested
(sub)-sections of output.  Unlike heading elements in HTML and other
common document formats, which precede the content that they head,
@code{heading} contains the elements that appear below the heading.

The document root heading, only, may contain a @code{pageSetup}
element.

The following attributes have been observed on both document root and
nested @code{heading} elements.

@defvr {Attribute} creator-version
The version of the software that created this SPV file.  A string of
the form @code{xxyyzzww} represents software version xx.yy.zz.ww,
e.g.@: @code{21000001} is version 21.0.0.1.  Trailing pairs of zeros
are sometimes omitted, so that @code{21}, @code{210000}, and
@code{21000000} are all version 21.0.0.0 (and the corpus contains all
three of those forms).
@end defvr

@noindent
The following attributes have been observed on document root
@code{heading} elements only:

@defvr {Attribute} @code{creator}
The directory in the file system of the software that created this SPV
file.
@end defvr

@defvr {Attribute} @code{creation-date-time}
The date and time at which the SPV file was written, in a
locale-specific format, e.g.@: @code{Friday, May 16, 2014 6:47:37 PM
PDT} or @code{lunedì 17 marzo 2014 3.15.48 CET} or even @code{Friday,
December 5, 2014 5:00:19 o'clock PM EST}.
@end defvr

@defvr {Attribute} @code{lockReader}
Whether a reader should be allowed to edit the output.  The possible
values are @code{true} and @code{false}.  The value @code{false} is by
far the most common.
@end defvr

@defvr {Attribute} @code{schemaLocation}
This is actually an XML Namespace attribute.  A reader may ignore it.
@end defvr

@noindent
The following attributes have been observed only on nested
@code{heading} elements:

@defvr {Attribute} @code{commandName}
A locale-invariant identifier for the command that produced the
output, e.g.@: @code{Frequencies}, @code{T-Test}, @code{Non Par Corr}.
@end defvr

@defvr {Attribute} @code{visibility}
To what degree the output represented by the element is visible.
@end defvr

@defvr {Attribute} @code{locale}
The locale used for output, in Windows format, which is similar to the
format used in Unix with the underscore replaced by a hyphen, e.g.@:
@code{en-US}, @code{en-GB}, @code{el-GR}, @code{sr-Cryl-RS}.
@end defvr

@defvr {Attribute} @code{olang}
The output language, e.g.@: @code{en}, @code{it}, @code{es},
@code{de}, @code{pt-BR}.
@end defvr

@node SPV Structure label Element
@subsection The @code{label} Element

@example
label => TEXT
@end example

Every @code{heading} and @code{container} holds a @code{label} as its
first child.  The label text is what appears in the outline pane of
the GUI's viewer window.  PSPP also puts it into the outline of PDF
output.  The label text doesn't appear in the output itself.

The text in @code{label} describes what it labels, often by naming the
statistical procedure that was executed, e.g.@: ``Frequencies'' or
``T-Test''.  The root @code{heading} in a structure member is normally
``Output''.  Labels are often very generic, especially within a
@code{container}, e.g.@: ``Title'' or ``Warnings'' or ``Notes''.
Label text is localized according to the output language, e.g.@: in
Italian a frequency table procedure is labeled ``Frequenze''.

The user can edit labels to be anything they want.  The corpus
contains a few examples of empty labels, ones that contain no text,
probably as a result of user editing.

@node SPV Structure container Element
@subsection The @code{container} Element

@example
container
   :visibility=(visible | hidden)
   :page-break-before=(always)?
   :text-align=(left | center)?
   :width=dimension
=> label (table | container_text | graph | model | object | image | tree)
@end example

A @code{container} serves to contain and label a @code{table},
@code{text}, or other kind of item.

This element has the following attributes.

@defvr {Attribute} @code{visibility}
Whether the container's content is displayed.  ``Notes'' tables are
often hidden; other data is usually
@end defvr

@defvr {Attribute} @code{text-align}
Alignment of text within the container.  Observed with nested
@code{table} and @code{text} elements.
@end defvr

@defvr {Attribute} @code{width}
The width of the container, e.g.@: @code{1097px}.
@end defvr

@node SPV Structure text Element (Inside @code{container})
@subsection The @code{text} Element (Inside @code{container})

@example
text[container_text]
  :type[text_type]=(title | log | text | page-title)
  :commandName?
  :creator-version?
=> html
@end example

This @code{text} element is nested inside a @code{container}.  There
is a different @code{text} element that is nested inside a
@code{pageParagraph}.

This element has the following attributes.

@defvr {Attribute} @code{type}
The semantics of the text.
@end defvr

@defvr {Attribute} @code{commandName}
As on the @code{heading} element.  For output not specific to a
command, this is simply @code{log}.  The corpus contains one example
of where @code{commandName} is present but set to the empty string.
@end defvr

@defvr {Attribute} @code{creator-version}
As on the @code{heading} element.
@end defvr

@node SPV Structure html Element
@subsection The @code{html} Element

@example
html :lang=(en) => TEXT
@end example

The element contains an HTML document as text (or, in practice, as
CDATA).  In some cases, the document starts with @code{<html>} and
ends with @code{</html>}; in others the @code{html} element is
implied.  Generally the HTML includes a @code{head} element with a CSS
stylesheet.  The HTML body often begins with @code{<BR>}.

The HTML document uses only the following elements:

@table @code
@item html
Sometimes, the document is enclosed with
@code{<html>}@dots{}@code{</html>}.

@item br
The HTML body often begins with @code{<BR>} and may contain it as well.

@item b
@itemx i
@itemx u
Styling.

@item font
The attributes @code{face}, @code{color}, and @code{size} are
observed.  The value of @code{color} takes one of the forms
@code{#@var{rr}@var{gg}@var{bb}} or @code{rgb (@var{r}, @var{g},
@var{b})}.  The value of @code{size} is a number between 1 and 7,
inclusive.
@end table

The CSS in the corpus is simple.  To understand it, a parser only
needs to be able to skip white space, @code{<!--}, and @code{-->}, and
parse style only for @code{p} elements.  Only the following properties
matter:

@table @code
@item color
In the form @code{@var{rr}@var{gg}@var{bb}}, e.g. @code{000000}, with
no leading @samp{#}.

@item font-weight
Either @code{bold} or @code{normal}.

@item font-style
Either @code{italic} or @code{normal}.

@item text-decoration
Either @code{underline} or @code{normal}.

@item font-family
A font name, commonly @code{Monospaced} or @code{SansSerif}.

@item font-size
Values claim to be in points, e.g.@: @code{14pt}, but the values are
actually in ``device-independent pixels'' (px), at 96/inch.
@end table

This element has the following attributes.

@defvr {Attribute} @code{lang}
This always contains @code{en} in the corpus.
@end defvr

@node SPV Structure table Element
@subsection The @code{table} Element

@example
table
   :VDPId?
   :ViZmlSource?
   :activePageId=int?
   :commandName
   :creator-version?
   :displayFiltering=bool?
   :maxNumCells=int?
   :orphanTolerance=int?
   :rowBreakNumber=int?
   :subType
   :tableId
   :tableLookId?
   :type[table_type]=(table | note | warning)
=> tableProperties? tableStructure

tableStructure => path? dataPath csvPath?
@end example

This element has the following attributes.

@defvr {Attribute} @code{commandName}
As on the @code{heading} element.
@end defvr

@defvr {Attribute} @code{type}
One of @code{table}, @code{note}, or @code{warning}.
@end defvr

@defvr {Attribute} @code{subType}
The locale-invariant command ID for the particular kind of output that
this table represents in the procedure.  This can be the same as
@code{commandName} e.g.@: @code{Frequencies}, or different, e.g.@:
@code{Case Processing Summary}.  Generic subtypes @code{Notes} and
@code{Warnings} are often used.
@end defvr

@defvr {Attribute} @code{tableId}
A number that uniquely identifies the table within the SPV file,
typically a large negative number such as @code{-4147135649387905023}.
@end defvr

@defvr {Attribute} @code{creator-version}
As on the @code{heading} element.  In the corpus, this is only present
for version 21 and up and always includes all 8 digits.
@end defvr

@xref{SPV Detail Legacy Properties}, for details on the
@code{tableProperties} element.

@node SPV Structure graph Element
@subsection The @code{graph} Element

@example
graph
   :VDPId?
   :ViZmlSource?
   :commandName?
   :creator-version?
   :dataMapId?
   :dataMapURI?
   :editor?
   :refMapId?
   :refMapURI?
   :csvFileIds?
   :csvFileNames?
=> dataPath? path csvPath?
@end example

This element represents a graph.  The @code{dataPath} and @code{path}
elements name the Zip members that give the details of the graph.
Normally, both elements are present; there is only one counterexample
in the corpus.

@code{csvPath} only appears in one SPV file in the corpus, for two
graphs.  In these two cases, @code{dataPath}, @code{path}, and
@code{csvPath} all appear.  These @code{csvPath} name Zip members with
names of the form @file{@var{number}_csv.bin}, where @var{number} is a
many-digit number and the same as the @code{csvFileIds}.  The named
Zip members are CSV text files (despite the @file{.bin} extension).
The CSV files are encoded in UTF-8 and begin with a U+FEFF byte-order
marker.

@node SPV Structure model Element
@subsection The @code{model} Element

@example
model
   :PMMLContainerId?
   :PMMLId
   :StatXMLContainerId
   :VDPId
   :auxiliaryViewName
   :commandName
   :creator-version
   :mainViewName
=> ViZml? dataPath? path | pmmlContainerPath statsContainerPath

pmmlContainerPath => TEXT

statsContainerPath => TEXT

ViZml :viewName? => TEXT
@end example

This element represents a model.  The @code{dataPath} and @code{path}
elements name the Zip members that give the details of the model.
Normally, both elements are present; there is only one counterexample
in the corpus.

The details are unexplored.  The @code{ViZml} element contains base-64
encoded text, that decodes to a binary format with some embedded text
strings, and @code{path} names an Zip member that contains XML.
Alternatively, @code{pmmlContainerPath} and @code{statsContainerPath}
name Zip members with @file{.scf} extension.

@node SPV Structure tree Element
@subsection The @code{tree} Element

@example
tree
   :commandName
   :creator-version
   :name
   :type
=> dataPath path
@end example

This element represents a tree.  The @code{dataPath} and @code{path}
elements name the Zip members that give the details of the tree.
The details are unexplored.

@node SPV Structure Path Elements
@subsection Path Elements

@example
dataPath => TEXT

path => TEXT

csvPath => TEXT
@end example

These element contain the name of the Zip members that hold details
for a container.  For tables:

@itemize @bullet
@item
When a ``light'' format is used, only @code{dataPath} is present, and
it names a @file{.bin} member of the Zip file that has @code{light} in
its name, e.g.@: @code{0000000001437_lightTableData.bin} (@pxref{SPV
Light Detail Member Format}).

@item
When the legacy format is used, both are present.  In this case,
@code{dataPath} names a Zip member with a legacy binary format that
contains relevant data (@pxref{SPV Legacy Detail Member Binary
Format}), and @code{path} names a Zip member that uses an XML format
(@pxref{SPV Legacy Detail Member XML Format}).
@end itemize

Graphs normally follow the legacy approach described above.  The
corpus contains one example of a graph with @code{path} but not
@code{dataPath}.  The reason is unexplored.

Models use @code{path} but not @code{dataPath}.  @xref{SPV Structure
graph Element}, for more information.

These elements have no attributes.

@node SPV Structure pageSetup Element
@subsection The @code{pageSetup} Element

@example
pageSetup
   :initial-page-number=int?
   :chart-size=(as-is | full-height | half-height | quarter-height | OTHER)?
   :margin-left=dimension?
   :margin-right=dimension?
   :margin-top=dimension?
   :margin-bottom=dimension?
   :paper-height=dimension?
   :paper-width=dimension?
   :reference-orientation?
   :space-after=dimension?
=> pageHeader pageFooter

pageHeader => pageParagraph?

pageFooter => pageParagraph?

pageParagraph => pageParagraph_text
@end example

The @code{pageSetup} element has the following attributes.

@defvr {Attribute} @code{initial-page-number}
The page number to put on the first page of printed output.  Usually
@code{1}.
@end defvr

@defvr {Attribute} @code{chart-size}
One of the listed, self-explanatory chart sizes,
@code{quarter-height}, or a localization (!) of one of these (e.g.@:
@code{dimensione attuale}, @code{Wie vorgegeben}).
@end defvr

@defvr {Attribute} @code{margin-left}
@defvrx {Attribute} @code{margin-right}
@defvrx {Attribute} @code{margin-top}
@defvrx {Attribute} @code{margin-bottom}
Margin sizes, e.g.@: @code{0.25in}.
@end defvr

@defvr {Attribute} @code{paper-height}
@defvrx {Attribute} @code{paper-width}
Paper sizes.
@end defvr

@defvr {Attribute} @code{reference-orientation}
Indicates the orientation of the output page.  Either @code{0deg}
(portrait) or @code{90deg} (landscape),
@end defvr

@defvr {Attribute} @code{space-after}
The amount of space between printed objects, typically @code{12pt}.
@end defvr

@node SPV Structure @code{text} Element (Inside @code{pageParagraph})
@subsection The @code{text} Element (Inside @code{pageParagraph})

@example
text[pageParagraph_text] :type=(title | text) => TEXT
@end example

This @code{text} element is nested inside a @code{pageParagraph}.  There
is a different @code{text} element that is nested inside a
@code{container}.

The element is either empty, or contains CDATA that holds almost-XHTML
text: in the corpus, either an @code{html} or @code{p} element.  It is
@emph{almost}-XHTML because the @code{html} element designates the
default namespace as
@indicateurl{http://xml.spss.com/spss/viewer/viewer-tree} instead of
an XHTML namespace, and because the CDATA can contain substitution
variables.  The following variables are supported:

@table @code
@item &[Date]
@itemx &[Time]
The current date or time in the preferred format for the locale.

@item &[Head1]
@itemx &[Head2]
@itemx &[Head3]
@itemx &[Head4]
First-, second-, third-, or fourth-level heading.

@item &[PageTitle]
The page title.

@item &[Filename]
Name of the output file.

@item &[Page]
The page number.
@end table

@code{&[Page]} for the page number and @code{&[PageTitle]} for the
page title.

Typical contents (indented for clarity):

@example
<html xmlns="http://xml.spss.com/spss/viewer/viewer-tree">
    <head></head>
    <body>
        <p style="text-align:right; margin-top: 0">Page &[Page]</p>
    </body>
</html>
@end example

This element has the following attributes.

@defvr {Attribute} @code{type}
Always @code{text}.
@end defvr

@node SPV Light Detail Member Format
@section Light Detail Member Format

This section describes the format of ``light'' detail @file{.bin}
members.  These members have a binary format which we describe here in
terms of a context-free grammar using the following conventions:

@table @asis
@item NonTerminal @result{} @dots{}
Nonterminals have CamelCaps names, and @result{} indicates a
production.  The right-hand side of a production is often broken
across multiple lines.  Break points are chosen for aesthetics only
and have no semantic significance.

@item 00, 01, @dots{}, ff.
A bytes with a fixed value, written as a pair of hexadecimal digits.

@item i0, i1, @dots{}, i9, i10, i11, @dots{}
@itemx ib0, ib1, @dots{}, ib9, ib10, ib11, @dots{}
A 32-bit integer in little-endian or big-endian byte order,
respectively, with a fixed value, written in decimal.  Prefixed by
@samp{i} for little-endian or @samp{ib} for big-endian.

@item byte
A byte.

@item bool
A byte with value 0 or 1.

@item int16
@itemx be16
A 16-bit unsigned integer in little-endian or big-endian byte order,
respectively.

@item int32
@itemx be32
A 32-bit unsigned integer in little-endian or big-endian byte order,
respectively.

@item int64
@itemx be64
A 64-bit unsigned integer in little-endian or big-endian byte order,
respectively.

@item double
A 64-bit IEEE floating-point number.

@item float
A 32-bit IEEE floating-point number.

@item string
@itemx bestring
A 32-bit unsigned integer, in little-endian or big-endian byte order,
respectively, followed by the specified number of bytes of UTF-8
encoded character data.

@item @var{x}?
@var{x} is optional, e.g.@: 00? is an optional zero byte.

@item @var{x}*@var{n}
@var{x} is repeated @var{n} times, e.g.@: byte*10 for ten arbitrary bytes.

@item @var{x}[@var{name}]
Gives @var{x} the specified @var{name}.  Names are used in textual
explanations.  They are also used, also bracketed, to indicate counts,
e.g.@: @code{int32[n] byte*[n]} for a 32-bit integer followed by the
specified number of arbitrary bytes.

@item @var{a} @math{|} @var{b}
Either @var{a} or @var{b}.

@item (@var{x})
Parentheses are used for grouping to make precedence clear, especially
in the presence of @math{|}, e.g.@: in 00 (01 @math{|} 02 @math{|} 03)
00.

@item count(@var{x})
@itemx becount(@var{x})
A 32-bit unsigned integer, in little-endian or big-endian byte order,
respectively, that indicates the number of bytes in @var{x}, followed
by @var{x} itself.

@item v1(@var{x})
In a version 1 @file{.bin} member, @var{x}; in version 3, nothing.
(The @file{.bin} header indicates the version.)

@item v3(@var{x})
In a version 3 @file{.bin} member, @var{x}; in version 1, nothing.
@end table

PSPP uses this grammar to parse light detail members.  See
@file{src/output/spv/light-binary.grammar} in the PSPP source tree for
the full grammar.

Little-endian byte order is far more common in this format, but a few
pieces of the format use big-endian byte order.

Light detail members express linear units in two ways: points (pt), at
72/inch, and ``device-independent pixels'' (px), at 96/inch.  To
convert from pt to px, multiply by 1.33 and round up.  To convert
from px to pt, divide by 1.33 and round down.

A ``light'' detail member @file{.bin} consists of a number of sections
concatenated together, terminated by an optional byte 01:

@example
LightMember =>
    Header Titles Footnotes
    Areas Borders PrintSettings TableSettings Formats
    Dimensions Axes Cells
    01?
@end example

The following sections go into more detail.

@menu
* SPV Light Member Header::
* SPV Light Member Titles::
* SPV Light Member Footnotes::
* SPV Light Member Areas::
* SPV Light Member Borders::
* SPV Light Member Print Settings::
* SPV Light Member Table Settings::
* SPV Light Member Formats::
* SPV Light Member Dimensions::
* SPV Light Member Categories::
* SPV Light Member Axes::
* SPV Light Member Cells::
* SPV Light Member Value::
* SPV Light Member ValueMod::
@end menu

@node SPV Light Member Header
@subsection Header

An SPV light member begins with a 39-byte header:

@example
Header =>
    01 00
    (i1 @math{|} i3)[version]
    bool[x0]
    bool[x1]
    bool[rotate-inner-column-labels]
    bool[rotate-outer-row-labels]
    bool[x2]
    int32[x3]
    int32[min-col-width] int32[max-col-width]
    int32[min-row-width] int32[max-row-width]
    int64[table-id]
@end example

@code{version} is a version number that affects the interpretation of
some of the other data in the member.  We will refer to ``version 1''
and ``version 3'' later on and use v1(@dots{}) and v3(@dots{}) for
version-specific formatting (as described previously).

If @code{rotate-inner-column-labels} is 1, then column labels closest
to the data are rotated to be vertical; otherwise, they are shown
in the normal way.

If @code{rotate-outer-row-labels} is 1, then row labels farthest from
the data are rotated to be vertical; otherwise, they are shown in the
normal way.

@code{table-id} is a binary version of the @code{tableId} attribute in
the structure member that refers to the detail member.  For example,
if @code{tableId} is @code{-4122591256483201023}, then @code{table-id}
would be 0xc6c99d183b300001.

@code{min-col-width} is the minimum width that a column will be
assigned automatically.  @code{max-col-width} is the maximum width
that a column will be assigned to accommodate a long column label.
@code{min-row-width} and @code{max-row-width} are a similar range for
the width of row labels.  All of these measurements are in 1/96 inch
units (called a ``device independent pixel'' unit in Windows).

The meaning of the other variable parts of the header is not known.  A
writer may safely use version 3, true for @code{x0}, false for
@code{x1}, true for @code{x2}, and 0x15 for @code{x3}.

@node SPV Light Member Titles
@subsection Titles

@example
Titles =>
    Value[title] 01?
    Value[subtype] 01? 31
    Value[user-title] 01?
    (31 Value[corner-text] @math{|} 58)
    (31 Value[caption] @math{|} 58)
@end example

The Titles follow the Header and specify the table's title, caption,
and corner text.

The @code{user-title} is shown above the title and reflects any user
editing of the title text or style.  The @code{title} is the title
originally generated by the procedure.  Both of these are appropriate
for presentation and localized to the user's language.  For example,
for a frequency table, @code{title} and @code{user-title} normally
name the variable and @code{c} is simply ``Frequencies''.

@code{subtype} is the same as the @code{subType} attribute in the
@code{table} structure XML element that referred to this member.
@xref{SPV Structure table Element}, for details.

The @code{corner-text}, if present, is shown in the upper-left corner
of the table, above the row headings and to the left of the column
headings.  It is usually absent.  Corner text prevents row dimension
labels from being displayed above the dimension's group and category
labels (see @code{show-row-labels-in-corner}).

The @code{caption}, if present, is shown below the table.
@code{caption} reflects user editing of the caption.

@node SPV Light Member Footnotes
@subsection Footnotes

@example
Footnotes => int32[n-footnotes] Footnote*[n-footnotes]
Footnote => Value[text] (58 @math{|} 31 Value[marker]) int32[show]
@end example

Each footnote has @code{text} and an optional custom @code{marker}
(such as @samp{*}).

The syntax for Value would allow footnotes (and their markers) to
reference other footnotes, but in practice this doesn't work.

@code{show} is a 32-bit signed integer.  It is positive to show the
footnote or negative to hide it.  Its magnitude is often 1, and in
other cases tends to be the number of references to the footnote.

@node SPV Light Member Areas
@subsection Areas

@example
Areas => 00? Area*8
Area =>
    byte[index] 31
    string[typeface] float[size] int32[style] bool[underline]
    int32[halign] int32[valign]
    string[fg-color] string[bg-color]
    bool[alternate] string[alt-fg-color] string[alt-bg-color]
    v3(int32[left-margin] int32[right-margin] int32[top-margin] int32[bottom-margin])
@end example

Each Area represents the style for a different area of the table, in
the following order: title, caption, footer, corner, column labels,
row labels, data, and layers.

@code{index} is the 1-based index of the Area, i.e. 1 for the first
Area, through 8 for the final Area.

@code{typeface} is the string name of the font used in the area.  In
the corpus, this is @code{SansSerif} in over 99% of instances and
@code{Times New Roman} in the rest.

@code{size} is the size of the font, in px (@pxref{SPV Light Detail
Member Format}) The most common size in the corpus is 12 px.  Even
though @code{size} has a floating-point type, in the corpus its values
are always integers.

@code{style} is a bit mask.  Bit 0 (with value 1) is set for bold, bit
1 (with value 2) is set for italic.

@code{underline} is 1 if the font is underlined, 0 otherwise.

@code{halign} specifies horizontal alignment: 0 for center, 2 for
left, 4 for right, 61453 for decimal, 64173 for mixed.  Mixed
alignment varies according to type: string data is left-justified,
numbers and most other formats are right-justified.

@code{valign} specifies vertical alignment: 0 for center, 1 for top, 3
for bottom.

@code{fg-color} and @code{bg-color} are the foreground color and
background color, respectively.  In the corpus, these are always
@code{#000000} and @code{#ffffff}, respectively.

@code{alternate} is 1 if rows should alternate colors, 0 if all rows
should be the same color.  When @code{alternate} is 1,
@code{alt-fg-color} and @code{alt-bg-color} specify the colors for the
alternate rows; otherwise they are empty strings.

@code{left-margin}, @code{right-margin}, @code{top-margin}, and
@code{bottom-margin} are measured in px.

@node SPV Light Member Borders
@subsection Borders

@example
Borders =>
    count(
        ib1[endian]
        be32[n-borders] Border*[n-borders]
        bool[show-grid-lines]
        00 00 00)

Border =>
    be32[border-type]
    be32[stroke-type]
    be32[color]
@end example

The Borders reflect how borders between regions are drawn.

The fixed value of @code{endian} can be used to validate the
endianness.

@code{show-grid-lines} is 1 to draw grid lines, otherwise 0.

Each Border describes one kind of border.  @code{n-borders} seems to
always be 19.  Each @code{border-type} appears once (although in an
unpredictable order) and correspond to the following borders:

@table @asis
@item 0
Title.
@item 1@dots{}4
Left, top, right, and bottom outer frame.
@item 5@dots{}8
Left, top, right, and bottom inner frame.
@item 9, 10
Left and top of data area.
@item 11, 12
Horizontal and vertical dimension rows.
@item 13, 14
Horizontal and vertical dimension columns.
@item 15, 16
Horizontal and vertical category rows.
@item 17, 18
Horizontal and vertical category columns.
@end table

@code{stroke-type} describes how a border is drawn, as one of:

@table @asis
@item 0
No line.
@item 1
Solid line.
@item 2
Dashed line.
@item 3
Thick line.
@item 4
Thin line.
@item 5
Double line.
@end table

@code{color} is an RGB color.  Bits 24--31 are alpha, bits 16--23 are
red, 8--15 are green, 0--7 are blue.  An alpha of 255 indicates an
opaque color, therefore opaque black is 0xff000000.

@node SPV Light Member Print Settings
@subsection Print Settings

@example
PrintSettings =>
    count(
        ib1[endian]
        bool[all-layers]
        bool[paginate-layers]
        bool[fit-width]
        bool[fit-length]
        bool[top-continuation]
        bool[bottom-continuation]
        be32[n-orphan-lines]
        bestring[continuation-string])
@end example

The PrintSettings reflect settings for printing.  The fixed value of
@code{endian} can be used to validate the endianness.

@code{all-layers} is 1 to print all layers, 0 to print only the
visible layers.

@code{paginate-layers} is 1 to print each layer at the start of a new
page, 0 otherwise.  (This setting is honored only @code{all-layers} is
1, since otherwise only one layer is printed.)

@code{fit-width} and @code{fit-length} control whether the table is
shrunk to fit within a page's width or length, respectively.

@code{n-orphan-lines} is the minimum number of rows or columns to put
in one part of a table that is broken across pages.

If @code{top-continuation} is 1, then @code{continuation-string} is
printed at the top of a page when a table is broken across pages for
printing; similarly for @code{bottom-continuation} and the bottom of a
page.  Usually, @code{continuation-string} is empty.

@node SPV Light Member Table Settings
@subsection Table Settings

@example
TableSettings =>
    count(
      v3(
        ib1[endian]
        be32[x5]
        be32[current-layer]
        bool[omit-empty]
        bool[show-row-labels-in-corner]
        bool[show-alphabetic-markers]
        bool[footnote-marker-superscripts]
        byte[x6]
        becount(
          Breakpoints[row-breaks] Breakpoints[column-breaks]
          Keeps[row-keeps] Keeps[column-keeps]
          PointKeeps[row-point-keeps] PointKeeps[column-point-keeps]
        )
        bestring[notes]
        bestring[table-look]
        00...))

Breakpoints => be32[n-breaks] be32*[n-breaks]

Keeps => be32[n-keeps] Keep*[n-keeps]
Keep => be32[offset] be32[n]

PointKeeps => be32[n-point-keeps] PointKeep*[n-point-keeps]
PointKeep => be32[offset] be32 be32
@end example

The TableSettings reflect display settings.  The fixed value of
@code{endian} can be used to validate the endianness.

@code{current-layer} is the displayed layer.  The interpretation when
there is more than one layer dimension is not yet known.

If @code{omit-empty} is 1, empty rows or columns (ones with nothing in
any cell) are hidden; otherwise, they are shown.

If @code{show-row-labels-in-corner} is 1, then row labels are shown in
the upper left corner; otherwise, they are shown nested.

If @code{show-alphabetic-markers} is 1, markers are shown as letters
(e.g.@: @samp{a}, @samp{b}, @samp{c}, @dots{}); otherwise, they are
shown as numbers starting from 1.

When @code{footnote-marker-superscripts} is 1, footnote markers are shown
as superscripts, otherwise as subscripts.

The Breakpoints are rows or columns after which there is a page break;
for example, a row break of 1 requests a page break after the second
row.  Usually no breakpoints are specified, indicating that page
breaks should be selected automatically.

The Keeps are ranges of rows or columns to be kept together without a
page break; for example, a row Keep with @code{offset} 1 and @code{n}
10 requests that the 10 rows starting with the second row be kept
together.  Usually no Keeps are specified.

The PointKeeps seem to be generated automatically based on
user-specified Keeps.  They seems to indicate a conversion from rows
or columns to pixel or point offsets.

@code{notes} is a text string that contains user-specified notes.  It
is displayed when the user hovers the cursor over the table, like text
in the @code{title} attribute in HTML.  It is not printed.  It is
usually empty.

@code{table-look} is the name of a SPSS ``TableLook'' table style,
such as ``Default'' or ``Academic''; it is often empty.

TableSettings ends with an arbitrary number of null bytes.  A writer
may safely write 82 null bytes.

A writer may safely use 4 for @code{x5} and 0 for @code{x6}.

@node SPV Light Member Formats
@subsection Formats

@example
Formats =>
    int32[n-widths] int32*[n-widths]
    string[locale]
    int32[current-layer]
    bool bool bool
    Y0
    CustomCurrency
    count(
      v1(X0?)
      v3(count(X1 count(X2)) count(X3)))
Y0 => int32[epoch] byte[decimal] byte[grouping]
CustomCurrency => int32[n-ccs] string*[n-ccs]
@end example

If @code{n-widths} is nonzero, then the accompanying integers are
column widths as manually adjusted by the user.

@code{locale} is a locale including an encoding, such as
@code{en_US.windows-1252} or @code{it_IT.windows-1252}.  The encoding
string (like other strings in the member) is encoded in UTF-8.

@code{epoch} is the year that starts the epoch.  A 2-digit year is
interpreted as belonging to the 100 years beginning at the epoch.  The
default epoch year is 69 years prior to the current year; thus, in
2017 this field by default contains 1948.  In the corpus, @code{epoch}
ranges from 1943 to 1948, plus some contain -1.

@code{decimal} is the decimal point character.  The observed values
are @samp{.} and @samp{,}.

@code{grouping} is the grouping character.  Usually, it is @samp{,} if
@code{decimal} is @samp{.}, and vice versa.  Other observed values are
@samp{'} (apostrophe), @samp{ } (space), and zero (presumably
indicating that digits should not be grouped).

@code{n-ccs} is observed as either 0 or 5.  When it is 5, the
following strings are CCA through CCE format strings.  @xref{Custom
Currency Formats,,, pspp, PSPP}.  Most commonly these are all
@code{-,,,} but other strings occur.

@subsubheading X0

X0 only appears, optionally, in version 1 members.

@example
X0 => byte*14 Y1 Y2
Y1 =>
    string[command] string[command-local]
    string[language] string[charset] string[locale]
    bool bool bool bool
    Y0
Y2 => CustomCurrency byte[missing] bool[x17]
@end example

@code{command} describes the statistical procedure that generated the
output, in English.  It is not necessarily the literal syntax name of
the procedure: for example, NPAR TESTS becomes ``Nonparametric
Tests.''  @code{command-local} is the procedure's name, translated
into the output language; it is often empty and, when it is not,
sometimes the same as @code{command}.

@code{dataset} is the name of the dataset analyzed to produce the
output, e.g.@: @code{DataSet1}, and @code{datafile} the name of the
file it was read from, e.g.@: @file{C:\Users\foo\bar.sav}.  The latter
is sometimes the empty string.

@code{missing} is the character used to indicate that a cell contains
a missing value.  It is always observed as @samp{.}.

X0 repeats @code{decimal}, @code{grouping}, CustomCurrency, and
@code{missing} already included in Formats.

A writer may safely use false for @code{x17}.

@subsubheading X1

X1 only appears in version 3 members.

@example
X1 =>
    bool
    byte[show-title]
    bool[x16]
    byte[lang]
    byte[show-variables]
    byte[show-values]
    int32[x18] int32[x19]
    00*17
    bool[x20]
    bool[show-caption]
@end example

@code{lang} may indicate the language in use.  Some values seem to be
0: @t{en}, 1: @t{de}, 2: @t{es}, 3: @t{it}, 5: @t{ko}, 6: @t{pl}, 8:
@t{zh-tw}, 10: @t{pt_BR}, 11: @t{fr}.  The @code{locale} in Formats
and the @code{language}, @code{charset}, and @code{locale} in X0 are
more likely to be useful in practice.

@code{show-variables} determines how variables are displayed by
default.  A value of 1 means to display variable names, 2 to display
variable labels when available, 3 to display both (name followed by
label, separated by a space).  The most common value is 0, which
probably means to use a global default.

@code{show-values} is a similar setting for values.  A value of 1
means to display the value, 2 to display the value label when
available, 3 to display both.  Again, the most common value is 0,
which probably means to use a global default.

@code{show-title} is 1 to show the caption, 10 to hide it.

@code{show-caption} is true to show the caption, false to hide it.

A writer may safely use false for @code{x14}, false
for @code{x16}, -1 for @code{x18} and @code{x19}, and false for
@code{x20}.

@subsubheading X2

X2 only appears in version 3 members.

@example
X2 =>
    int32[n-row-heights] int32*[n-row-heights]
    int32[n-style-map] StyleMap*[n-style-map]
    int32[n-styles] StylePair*[n-styles]
    count((i0 i0)?)
StyleMap => int64[cell-index] int16[style-index]
@end example

If present, @code{n-row-heights} and the accompanying integers are row
heights as manually adjusted by the user.

The rest of X2 specifies styles for data cells.  At first glance this
is odd, because each data cell can have its own style embedded as part
of the data, but in practice X2 specifies a style for a cell only if
that cell is empty (and thus does not appear in the data at all).
Each StyleMap specifies the index of a blank cell, calculated the same
was as in the Cells (@pxref{SPV Light Member Cells}), along with a
0-based index into the accompanying StylePair array.

A writer may safely omit the optional @code{i0 i0} inside the
@code{count(@dots{})}.

@subsubheading X3

X3 only appears in version 3 members.

@example
X3 =>
    01 00 byte[x21] 00 00 00
    Y1
    double[small] 01
    (string[dataset] string[datafile] i0 int32[date] i0)?
    Y2
    (int32[x22] i0)?
@end example

@code{date} is a date, as seconds since the epoch, i.e.@: since
January 1, 1970.  Pivot tables within an SPV file often have dates a
few minutes apart, so this is probably a creation date for the table
rather than for the file.

X3 repeats @code{decimal}, @code{grouping}, CustomCurrency, and
@code{missing} already included in Formats.  @code{command},
@code{command-local}, @code{language}, @code{charset}, and
@code{locale} have the same meaning as in X0.

@code{small} is a small real number.  In the corpus, it overwhelmingly
takes the value 0.0001, with zero occasionally seen.  Nonzero numbers
with format 40 (@pxref{SPV Light Member Value}) whose magnitudes are
smaller than displayed in scientific notation.  (Thus, a @code{small}
of zero prevents scientific notation from being chosen.)

Sometimes @code{dataset}, @code{datafile}, and @code{date} are present
and other times they are absent.  The reader can distinguish by
assuming that they are present and then checking whether the
presumptive @code{dataset} contains a null byte (a valid string never
will).

@code{x22} is usually 0 or 2000000.

A writer may safely use 4 for @code{x21} and omit @code{x22} and the
other optional bytes at the end.

@node SPV Light Member Dimensions
@subsection Dimensions

A pivot table presents multidimensional data.  A Dimension identifies
the categories associated with each dimension.

@example
Dimensions => int32[n-dims] Dimension*[n-dims]
Dimension =>
    Value[name] DimProperties
    int32[n-categories] Category*[n-categories]
DimProperties =>
    byte[x1]
    byte[x2]
    int32[x3]
    bool[hide-dim-label]
    bool[hide-all-labels]
    01 int32[dim-index]
@end example

@code{name} is the name of the dimension, e.g.@: @code{Variables},
@code{Statistics}, or a variable name.

The meanings of @code{x1} and @code{x3} are unknown.  @code{x1} is
usually 0 but many other values have been observed.  A writer may
safely use 0 for @code{x1} and 2 for @code{x3}.

@code{x2} is 0, 1, or 2.  For a pivot table with @var{L} layer
dimensions, @var{R} row dimensions, and @var{C} column dimensions,
@code{x2} is 2 for the first @var{L} dimensions, 0 for the next
@var{R} dimensions, and 1 for the remaining @var{C} dimensions.  This
does not mean that the layer dimensions must be presented first,
followed by the row dimensions, followed by the column dimensions---on
the contrary, they are frequently in a different order---but @code{x2}
must follow this pattern to prevent the pivot table from being
misinterpreted.

If @code{hide-dim-label} is 00, the pivot table displays a label for
the dimension itself.  Because usually the group and category labels
are enough explanation, it is usually 01.

If @code{hide-all-labels} is 01, the pivot table omits all labels for
the dimension, including group and category labels.  It is usually 00.
When @code{hide-all-labels} is 01, @code{show-dim-label} is ignored.

@code{dim-index} is usually the 0-based index of the dimension, e.g.@:
0 for the first dimension, 1 for the second, and so on.  Sometimes it
is -1.  There is no visible difference.

@node SPV Light Member Categories
@subsection Categories

Categories are arranged in a tree.  Only the leaf nodes in the tree
are really categories; the others just serve as grouping constructs.

@example
Category => Value[name] (Leaf @math{|} Group)
Leaf => 00 00 00 i2 int32[leaf-index] i0
Group =>
    bool[merge] 00 01 int32[x23]
    i-1 int32[n-subcategories] Category*[n-subcategories]
@end example

@code{name} is the name of the category (or group).

A Leaf represents a leaf category.  The Leaf's @code{leaf-index} is a
nonnegative integer unique within the Dimension and less than
@code{n-categories} in the Dimension.  If the user does not sort or
rearrange the categories, then @code{leaf-index} starts at 0 for the
first Leaf in the dimension and increments by 1 with each successive
Leaf.  If the user does sorts or rearrange the categories, then the
order of categories in the file reflects that change and
@code{leaf-index} reflects the original order.

Occasionally a dimension has no leaf categories at all.  A table that
contains such a dimension necessarily has no data at all.

A Group is a group of nested categories.  Usually a Group contains at
least one Category, so that @code{n-subcategories} is positive, but a
few Groups with @code{n-subcategories} 0 has been observed.

If a Group's @code{merge} is 00, the most common value, then the group
is really a distinct group that should be represented as such in the
visual representation and user interface.  If @code{merge} is 01, the
categories in this group should be shown and treated as if they were
direct children of the group's containing group (or if it has no
parent group, then direct children of the dimension), and this group's
name is irrelevant and should not be displayed.  (Merged groups can be
nested!)

(For writing an SPV file, there is no need to use the @code{merge}
feature unless it is convenient.)

A Group's @code{x23} appears to be i2 when all of the categories
within a group are leaf categories that directly represent data values
for a variable (e.g.@: in a frequency table or crosstabulation, a group
of values in a variable being tabulated) and i0 otherwise.  A writer
may safely write a constant 0 in this field.

@node SPV Light Member Axes
@subsection Axes

After the dimensions come assignment of each dimension to one of the
axes: layers, rows, and columns.

@example
Axes =>
    int32[n-layers] int32[n-rows] int32[n-columns]
    int32*[n-layers] int32*[n-rows] int32*[n-columns]
@end example

The values of @code{n-layers}, @code{n-rows}, and @code{n-columns}
each specifies the number of dimensions displayed in layers, rows, and
columns, respectively.  Any of them may be zero.  Their values sum to
@code{n-dimensions} from Dimensions (@pxref{SPV Light Member
Dimensions}).

The following @code{n-dimensions} integers, in three groups, are a
permutation of the 0-based dimension numbers.  The first
@code{n-layers} integers specify each of the dimensions represented by
layers, the next @code{n-rows} integers specify the dimensions
represented by rows, and the final @code{n-columns} integers specify
the dimensions represented by columns.  When there is more than one
dimension of a given kind, the inner dimensions are given first.

@node SPV Light Member Cells
@subsection Cells

The final part of an SPV light member contains the actual data.

@example
Cells => int32[n-cells] Cell*[n-cells]
Cell => int64[index] v1(00?) Value
@end example

A Cell consists of an @code{index} and a Value.  Suppose there are
@math{d} dimensions, numbered 1 through @math{d} in the order given in
the Dimensions previously, and that dimension @math{i}, has @math{n_i}
categories.  Consider the cell at coordinates @math{x_i}, @math{1 \le
i \le d}, and note that @math{0 \le x_i < n_i}.  Then the index is
calculated by the following algorithm:

@display
let @i{index} = 0
for each @math{i} from 1 to @math{d}:
    @i{index} = (@math{n_i \times} @i{index}) @math{+} @math{x_i}
@end display

For example, suppose there are 3 dimensions with 3, 4, and 5
categories, respectively.  The cell at coordinates (1, 2, 3) has
index @math{5 \times (4 \times (3 \times 0 + 1) + 2) + 3 = 33}.
Within a given dimension, the index is the @code{leaf-index} in a Leaf.

@node SPV Light Member Value
@subsection Value

Value is used throughout the SPV light member format.  It boils down
to a number or a string.

@example
Value => 00? 00? 00? 00? RawValue
RawValue =>
    01 ValueMod int32[format] double[x]
  @math{|} 02 ValueMod int32[format] double[x]
    string[var-name] string[value-label] byte[show]
  @math{|} 03 string[local] ValueMod string[id] string[c] bool[fixed]
  @math{|} 04 ValueMod int32[format] string[value-label] string[var-name]
    byte[show] string[s]
  @math{|} 05 ValueMod string[var-name] string[var-label] byte[show]
  @math{|} ValueMod string[template] int32[n-args] Argument*[n-args]
Argument =>
    i0 Value
  @math{|} int32[x] i0 Value*[x]      /* x > 0 */
@end example

There are several possible encodings, which one can distinguish by the
first nonzero byte in the encoding.

@table @asis
@item 01
The numeric value @code{x}, intended to be presented to the user
formatted according to @code{format}, which is about the same as the
format described for system files (@pxref{System File Output
Formats}).  The exception is that format 40 is not MTIME but instead
approximately a synonym for F format with a different rule for whether
a value is shown in scientific notation: a value in format 40 is shown
in scientific notation if and only if it is nonzero and its magnitude
is less than @code{small} (@pxref{SPV Light Member Formats}).

Most commonly, @code{format} has width 40 (the maximum).

An @code{x} with the maximum negative double value @code{-DBL_MAX}
represents the system-missing value SYSMIS.  (HIGHEST and LOWEST have
not been observed.)  @xref{System File Format}, for more about these
special values.

@item 02
Similar to @code{01}, with the additional information that @code{x} is
a value of variable @code{var-name} and has value label
@code{value-label}.  Both @code{var-name} and @code{value-label} can
be the empty string, the latter very commonly.

@code{show} determines whether to show the numeric value or the value
label.  A value of 1 means to show the value, 2 to show the label, 3
to show both, and 0 means to use the default specified in
@code{show-values} (@pxref{SPV Light Member Formats}).

@item 03
A text string, in two forms: @code{c} is in English, and sometimes
abbreviated or obscure, and @code{local} is localized to the user's
locale.  In an English-language locale, the two strings are often the
same, and in the cases where they differ, @code{local} is more
appropriate for a user interface, e.g.@: @code{c} of ``Not a PxP table
for MCN...'' versus @code{local} of ``Computed only for a PxP table,
where P must be greater than 1.''

@code{c} and @code{local} are always either both empty or both
nonempty.

@code{id} is a brief identifying string whose form seems to resemble a
programming language identifier, e.g.@: @code{cumulative_percent} or
@code{factor_14}.  It is not unique.

@code{fixed} is 00 for text taken from user input, such as syntax
fragment, expressions, file names, data set names, and 01 for fixed
text strings such as names of procedures or statistics.  In the former
case, @code{id} is always the empty string; in the latter case,
@code{id} is still sometimes empty.

@item 04
The string value @code{s}, intended to be presented to the user
formatted according to @code{format}.  The format for a string is not
too interesting, and the corpus contains many clearly invalid formats
like A16.39 or A255.127 or A134.1, so readers should probably entirely
disregard the format.  PSPP only checks @code{format} to distinguish
AHEX format.

@code{s} is a value of variable @code{var-name} and has value label
@code{value-label}.  @code{var-name} is never empty but
@code{value-label} is commonly empty.

@code{show} has the same meaning as in the encoding for 02.

@item 05
Variable @code{var-name}, which is rarely observed as empty in the
corpus, with variable label @code{var-label}, which is often empty.

@code{show} determines whether to show the variable name or the
variable label.  A value of 1 means to show the name, 2 to show the
label, 3 to show both, and 0 means to use the default specified in
@code{show-variables} (@pxref{SPV Light Member Formats}).

@item otherwise
When the first byte of a RawValue is not one of the above, the
RawValue starts with a ValueMod, whose syntax is described in the next
section.  (A ValueMod always begins with byte 31 or 58.)

This case is a template string, analogous to @code{printf}, followed
by one or more Arguments, each of which has one or more values.  The
template string is copied directly into the output except for the
following special syntax,

@table @code
@item \%
@itemx \:
@itemx \[
@itemx \]
Each of these expands to the character following @samp{\\}, to escape
characters that have special meaning in template strings.  These are
effective inside and outside the @code{[@dots{}]}  syntax forms
described below.

@item \n
Expands to a new-line, inside or outside the @code{[@dots{}]} forms
described below.

@item ^@var{i}
Expands to a formatted version of argument @var{i}, which must have
only a single value.  For example, @code{^1} expands to the first
argument's @code{value}.

@item [:@var{a}:]@var{i}
Expands @var{a} for each of the values in @var{i}.  @var{a}
should contain one or more @code{^@var{j}} conversions, which are
drawn from the values for argument @var{i} in order.  Some examples
from the corpus:

@table @code
@item [:^1:]1
All of the values for the first argument, concatenated.

@item [:^1\n:]1
Expands to the values for the first argument, each followed by
a new-line.

@item [:^1 = ^2:]2
Expands to @code{@var{x} = @var{y}} where @var{x} is the second
argument's first value and @var{y} is its second value.  (This would
be used only if the argument has two values.  If there were more
values, the second and third values would be directly concatenated,
which would look funny.)
@end table

@item [@var{a}:@var{b}:]@var{i}
This extends the previous form so that the first values are expanded
using @var{a} and later values are expanded using @var{b}.  For an
unknown reason, within @var{a} the @code{^@var{j}} conversions are
instead written as @code{%@var{j}}.  Some examples from the corpus:

@table @code
@item [%1:*^1:]1
Expands to all of the values for the first argument, separated by
@samp{*}.

@item [%1 = %2:, ^1 = ^2:]1
Given appropriate values for the first argument, expands to @code{X =
1, Y = 2, Z = 3}.

@item [%1:, ^1:]1
Given appropriate values, expands to @code{1, 2, 3}.
@end table
@end table

The template string is localized to the user's locale.
@end table

A writer may safely omit all of the optional 00 bytes at the beginning
of a Value, except that it should write a single 00 byte before a
templated Value.

@node SPV Light Member ValueMod
@subsection ValueMod

A ValueMod can specify special modifications to a Value.

@example
ValueMod =>
    58
  @math{|} 31
    int32[n-refs] int16*[n-refs]
    int32[n-subscripts] string*[n-subscripts]
    v1(00 (i1 | i2) 00? 00? int32 00? 00?)
    v3(count(TemplateString StylePair))

TemplateString => count((count((i0 (58 @math{|} 31 55))?) (58 @math{|} 31 string[id]))?)

StylePair =>
    (31 FontStyle | 58)
    (31 CellStyle | 58)

FontStyle =>
    bool[bold] bool[italic] bool[underline] bool[show]
    string[fg-color] string[bg-color]
    string[typeface] byte[size]

CellStyle =>
    int32[halign] int32[valign] double[decimal-offset]
    int16[left-margin] int16[right-margin]
    int16[top-margin] int16[bottom-margin]
@end example

A ValueMod that begins with ``31'' specifies special modifications to
a Value.

Each of the @code{n-refs} integers is a reference to a Footnote
(@pxref{SPV Light Member Footnotes}) by 0-based index.  Footnote
markers are shown appended to the main text of the Value, as
superscripts.

The @code{subscripts}, if present, are strings to append to the main
text of the Value, as subscripts.  Each subscript text is a brief
indicator, e.g.@: @samp{a} or @samp{b}, with its meaning indicated by
the table caption.  When multiple subscripts are present, they are
displayed separated by commas.

The @code{id} inside the TemplateString, if present, is a template
string for substitutions using the syntax explained previously.  It
appears to be an English-language version of the localized template
string in the Value in which the Template is nested.  A writer may
safely omit the optional fixed data in TemplateString.

FontStyle and CellStyle, if present, change the style for this
individual Value.  In FontStyle, @code{bold}, @code{italic}, and
@code{underline} control the particular style.  @code{show} is
ordinarily 1; if it is 0, then the cell data is not shown.
@code{fg-color} and @code{bg-color} are strings in the format
@code{#rrggbb}, e.g.@: @code{#ff0000} for red or @code{#ffffff} for
white.  The empty string is occasionally observed also.  The
@code{size} is a font size in units of 1/128 inch.

In CellStyle, @code{halign} is 0 for center, 2 for left, 4 for right,
6 for decimal, 0xffffffad for mixed.  For decimal alignment,
@code{decimal-offset} is the decimal point's offset from the right
side of the cell, in pt (@pxref{SPV Light Detail Member Format}).
@code{valign} specifies vertical alignment: 0 for center, 1 for top, 3
for bottom.  @code{left-margin}, @code{right-margin},
@code{top-margin}, and @code{bottom-margin} are in pt.

@node SPV Legacy Detail Member Binary Format
@section Legacy Detail Member Binary Format

Whereas the light binary format represents everything about a given
pivot table, the legacy binary format conceptually consists of a
number of named sources, each of which consists of a number of named
variables, each of which is a 1-dimensional array of numbers or
strings or a mix.  Thus, the legacy binary member format is quite
simple.

This section uses the same context-free grammar notation as in the
previous section, with the following additions:

@table @asis
@item vAF(@var{x})
In a version 0xaf legacy member, @var{x}; in other versions, nothing.
(The legacy member header indicates the version; see below.)

@item vB0(@var{x})
In a version 0xb0 legacy member, @var{x}; in other versions, nothing.
@end table

A legacy detail member @file{.bin} has the following overall format:

@example
LegacyBinary =>
    00 byte[version] int16[n-sources] int32[member-size]
    Metadata*[n-sources]
    #Data*[n-sources]
    #Strings?
@end example

@code{version} is a version number that affects the interpretation of
some of the other data in the member.  Versions 0xaf and 0xb0 are
known.  We will refer to ``version 0xaf'' and ``version 0xb0'' members
later on.

A legacy member consists of @code{n-sources} data sources, each of
which has Metadata and Data.

@code{member-size} is the size of the legacy binary member, in bytes.

The Data and Strings above are commented out because the Metadata has
some oddities that mean that the Data sometimes seems to start at
an unexpected place.  The following section goes into detail.

@menu
* SPV Legacy Member Metadata::
* SPV Legacy Member Numeric Data::
* SPV Legacy Member String Data::
@end menu

@node SPV Legacy Member Metadata
@subsection Metadata

@example
Metadata =>
    int32[n-values] int32[n-variables] int32[data-offset]
    vAF(byte*28[source-name])
    vB0(byte*64[source-name] int32[x])
@end example

A data source has @code{n-variables} variables, each with
@code{n-values} data values.

@code{source-name} is a 28- or 64-byte string padded on the right with
0-bytes.  The names that appear in the corpus are very generic:
usually @code{tableData} for pivot table data or @code{source0} for
chart data.

A given Metadata's @code{data-offset} is the offset, in bytes, from
the beginning of the member to the start of the corresponding Data.
This allows programs to skip to the beginning of the data for a
particular source.  In every case in the corpus, the Data follow the
Metadata in the same order, but it is important to use
@code{data-offset} instead of reading sequentially through the file
because of the exception described below.

One SPV file in the corpus has legacy binary members with version 0xb0
but a 28-byte @code{source-name} field (and only a single source).  In
practice, this means that the 64-byte @code{source-name} used in
version 0xb0 has a lot of 0-bytes in the middle followed by the
@code{variable-name} of the following Data.  As long as a reader
treats the first 0-byte in the @code{source-name} as terminating the
string, it can properly interpret these members.

The meaning of @code{x} in version 0xb0 is unknown.

@node SPV Legacy Member Numeric Data
@subsection Numeric Data

@example
Data => Variable*[n-variables]
Variable => byte*288[variable-name] double*[n-values]
@end example

Data follow the Metadata in the legacy binary format, with sources in
the same order (but readers should use the @code{data-offset} in
Metadata records, rather than reading sequentially).  Each Variable
begins with a @code{variable-name} that generally indicates its role
in the pivot table, e.g.@: ``cell'', ``cellFormat'',
``dimension0categories'', ``dimension0group0'', followed by the
numeric data, one double per datum.  A double with the maximum
negative double @code{-DBL_MAX} represents the system-missing value
SYSMIS.

@node SPV Legacy Member String Data
@subsection String Data

@example
Strings => SourceMaps[maps] Labels

SourceMaps => int32[n-maps] SourceMap*[n-maps]

SourceMap => string[source-name] int32[n-variables] VariableMap*[n-variables]
VariableMap => string[variable-name] int32[n-data] DatumMap*[n-data]
DatumMap => int32[value-idx] int32[label-idx]

Labels => int32[n-labels] Label*[n-labels]
Label => int32[frequency] string[label]
@end example

Each variable may include a mix of numeric and string data values.  If
a legacy binary member contains any string data, Strings is present;
otherwise, it ends just after the last Data element.

The string data overlays the numeric data.  When a variable includes
any string data, its Variable represents the string values with a
SYSMIS or NaN placeholder.  (Not all such values need be
placeholders.)

Each SourceMap provides a mapping between SYSMIS or NaN values in source
@code{source-name} and the string data that they represent.
@code{n-variables} is the number of variables in the source that
include string data.  More precisely, it is the 1-based index of the
last variable in the source that includes any string data; thus, it
would be 4 if there are 5 variables and only the fourth one includes
string data.

A VariableMap repeats its variable's name, but variables are always
present in the same order as the source, starting from the first
variable, without skipping any even if they have no string values.
Each VariableMap contains DatumMap nonterminals, each of which maps
from a 0-based index within its variable's data to a 0-based label
index, e.g.@: pair @code{value-idx} = 2, @code{label-idx} = 3, means
that the third data value (which must be SYSMIS or NaN) is to be
replaced by the string of the fourth Label.

The labels themselves follow the pairs.  The valuable part of each
label is the string @code{label}.  Each label also includes a
@code{frequency} that reports the number of DatumMaps that reference
it (although this is not useful).

@node SPV Legacy Detail Member XML Format
@section Legacy Detail Member XML Format

The design of the detail XML format is not what one would end up with
for describing pivot tables.  This is because it is a special case
of a much more general format (``visualization XML'' or ``VizML'')
that can describe a wide range of visualizations.  Most of this
generality is overkill for tables, and so we end up with a funny
subset of a general-purpose format.

An XML Schema for VizML is available, distributed with SPSS binaries,
under a nonfree license.  It contains documentation that is
occasionally helpful.

This section describes the detail XML format using the same notation
already used for the structure XML format (@pxref{SPV Structure Member
Format}).  See @file{src/output/spv/detail-xml.grammar} in the PSPP
source tree for the full grammar that it uses for parsing.

The important elements of the detail XML format are:

@itemize @bullet
@item
Variables.  @xref{SPV Detail Variable Elements}.

@item
Assignment of variables to axes.  A variable can appear as columns, or
rows, or layers.  The @code{faceting} element and its sub-elements
describe this assignment.

@item
Styles and other annotations.
@end itemize

This description is not detailed enough to write legacy tables.
Instead, write tables in the light binary format.

@menu
* SPV Detail visualization Element::
* SPV Detail Variable Elements::
* SPV Detail extension Element::
* SPV Detail graph Element::
* SPV Detail location Element::
* SPV Detail faceting Element::
* SPV Detail facetLayout Element::
* SPV Detail label Element::
* SPV Detail setCellProperties Element::
* SPV Detail setFormat Element::
* SPV Detail interval Element::
* SPV Detail style Element::
* SPV Detail labelFrame Element::
* SPV Detail Legacy Properties::
@end menu

@node SPV Detail visualization Element
@subsection The @code{visualization} Element

@example
visualization
   :creator
   :date
   :lang
   :name
   :style[style_ref]=ref style
   :type
   :version
   :schemaLocation?
=> visualization_extension?
   userSource
   (sourceVariable | derivedVariable)+
   categoricalDomain?
   graph
   labelFrame[lf1]*
   container?
   labelFrame[lf2]*
   style+
   layerController?

extension[visualization_extension]
   :numRows=int?
   :showGridline=bool?
   :minWidthSet=(true)?
   :maxWidthSet=(true)?
=> EMPTY

userSource :missing=(listwise | pairwise)? => EMPTY

categoricalDomain => variableReference simpleSort

simpleSort :method[sort_method]=(custom) => categoryOrder

container :style=ref style => container_extension? location+ labelFrame*

extension[container_extension] :combinedFootnotes=(true) => EMPTY

layerController
   :source=(tableData)
   :target=ref label?
=> EMPTY
@end example

The @code{visualization} element is the root of detail XML member.  It
has the following attributes:

@defvr {Attribute} creator
The version of the software that created this SPV file, as a string of
the form @code{xxyyzz}, which represents software version xx.yy.zz,
e.g.@: @code{160001} is version 16.0.1.  The corpus includes major
versions 16 through 19.
@end defvr

@defvr {Attribute} date
The date on the which the file was created, as a string of the form
@code{YYYY-MM-DD}.
@end defvr

@defvr {Attribute} lang
The locale used for output, in Windows format, which is similar to the
format used in Unix with the underscore replaced by a hyphen, e.g.@:
@code{en-US}, @code{en-GB}, @code{el-GR}, @code{sr-Cryl-RS}.
@end defvr

@defvr {Attribute} name
The title of the pivot table, localized to the output language.
@end defvr

@defvr {Attribute} style
The base style for the pivot table.  In every example in the corpus,
the @code{style} element has no attributes other than @code{id}.
@end defvr

@defvr {Attribute} type
A floating-point number.  The meaning is unknown.
@end defvr

@defvr {Attribute} version
The visualization schema version number.  In the corpus, the value is
one of 2.4, 2.5, 2.7, and 2.8.
@end defvr

The @code{userSource} element has no visible effect.

The @code{extension} element as a child of @code{visualization} has
the following attributes.

@defvr {Attribute} numRows
An integer that presumably defines the number of rows in the displayed
pivot table.
@end defvr

@defvr {Attribute} showGridline
Always set to @code{false} in the corpus.
@end defvr

@defvr {Attribute} minWidthSet
@defvrx {Attribute} maxWidthSet
Always set to @code{true} in the corpus.
@end defvr

The @code{extension} element as a child of @code{container} has the
following attribute

@defvr {Attribute} combinedFootnotes
Meaning unknown.
@end defvr

The @code{categoricalDomain} and @code{simpleSort} elements have no
visible effect.

The @code{layerController} element has no visible effect.

@node SPV Detail Variable Elements
@subsection Variable Elements

A ``variable'' in detail XML is a 1-dimensional array of data.  Each
element of the array may, independently, have string or numeric
content.  All of the variables in a given detail XML member either
have the same number of elements or have zero elements.

Two different elements define variables and their content:

@table @code
@item sourceVariable
These variables' data comes from the associated @code{tableData.bin}
member.

@item derivedVariable
These variables are defined in terms of a mapping function from a
source variable, or they are empty.
@end table

A variable named @code{cell} always exists.  This variable holds the
data displayed in the table.

Variables in detail XML roughly correspond to the dimensions in a
light detail member.  Each dimension has the following variables with
stylized names, where @var{n} is a number for the dimension starting
from 0:

@table @code
@item dimension@var{n}categories
The dimension's leaf categories (@pxref{SPV Light Member Categories}).

@item dimension@var{n}group0
Present only if the dimension's categories are grouped, this variable
holds the group labels for the categories.  Grouping is inferred
through adjacent identical labels.  Categories that are not part of a
group have empty-string data in this variable.

@item dimension@var{n}group1
Present only if the first-level groups are further grouped, this
variable holds the labels for the second-level groups.  There can be
additional variables with further levels of grouping.

@item dimension@var{n}
An empty variable.
@end table

Determining the data for a (non-empty) variable is a multi-step
process:

@enumerate
@item
Draw initial data from its source, for a @code{sourceVariable}, or
from another named variable, for a @code{derivedVariable}.

@item
Apply mappings from @code{valueMapEntry} elements within the
@code{derivedVariable} element, if any.

@item
Apply mappings from @code{relabel} elements within a @code{format} or
@code{stringFormat} element in the @code{sourceVariable} or
@code{derivedVariable} element, if any.

@item
If the variable is a @code{sourceVariable} with a @code{labelVariable}
attribute, and there were no mappings to apply in previous steps, then
replace each element of the variable by the corresponding value in the
label variable.
@end enumerate

A single variable's data can be modified in two of the steps, if both
@code{valueMapEntry} and @code{relabel} are used.  The following
example from the corpus maps several integers to 2, then maps 2 in
turn to the string ``Input'':

@example
<derivedVariable categorical="true" dependsOn="dimension0categories"
                 id="dimension0group0map" value="map(dimension0group0)">
  <stringFormat>
    <relabel from="2" to="Input"/>
    <relabel from="10" to="Missing Value Handling"/>
    <relabel from="14" to="Resources"/>
    <relabel from="0" to=""/>
    <relabel from="1" to=""/>
    <relabel from="13" to=""/>
  </stringFormat>
  <valueMapEntry from="2;3;5;6;7;8;9" to="2"/>
  <valueMapEntry from="10;11" to="10"/>
  <valueMapEntry from="14;15" to="14"/>
  <valueMapEntry from="0" to="0"/>
  <valueMapEntry from="1" to="1"/>
  <valueMapEntry from="13" to="13"/>
</derivedVariable>
@end example

@menu
* SPV Detail sourceVariable Element::
* SPV Detail derivedVariable Element::
* SPV Detail valueMapEntry Element::
@end menu

@node SPV Detail sourceVariable Element
@subsubsection The @code{sourceVariable} Element

@example
sourceVariable
   :id
   :categorical=(true)
   :source
   :domain=ref categoricalDomain?
   :sourceName
   :dependsOn=ref sourceVariable?
   :label?
   :labelVariable=ref sourceVariable?
=> variable_extension* (format | stringFormat)?
@end example

This element defines a variable whose data comes from the
@file{tableData.bin} member that corresponds to this @file{.xml}.

This element has the following attributes.

@defvr {Attribute} id
An @code{id} is always present because this element exists to be
referenced from other elements.
@end defvr

@defvr {Attribute} categorical
Always set to @code{true}.
@end defvr

@defvr {Attribute} source
Always set to @code{tableData}, the @code{source-name} in the
corresponding @file{tableData.bin} member (@pxref{SPV Legacy Member
Metadata}).
@end defvr

@defvr {Attribute} sourceName
The name of a variable within the source, corresponding to the
@code{variable-name} in the @file{tableData.bin} member (@pxref{SPV
Legacy Member Numeric Data}).
@end defvr

@defvr {Attribute} label
The variable label, if any.
@end defvr

@defvr {Attribute} labelVariable
The @code{variable-name} of a variable whose string values correspond
one-to-one with the values of this variable and are suitable for use
as value labels.
@end defvr

@defvr {Attribute} dependsOn
This attribute doesn't affect the display of a table.
@end defvr

@node SPV Detail derivedVariable Element
@subsubsection The @code{derivedVariable} Element

@example
derivedVariable
   :id
   :categorical=(true)
   :value
   :dependsOn=ref sourceVariable?
=> variable_extension* (format | stringFormat)? valueMapEntry*
@end example

Like @code{sourceVariable}, this element defines a variable whose
values can be used elsewhere in the visualization.  Instead of being
read from a data source, the variable's data are defined by a
mathematical expression.

This element has the following attributes.

@defvr {Attribute} id
An @code{id} is always present because this element exists to be
referenced from other elements.
@end defvr

@defvr {Attribute} categorical
Always set to @code{true}.
@end defvr

@defvr {Attribute} value
An expression that defines the variable's value.  In theory this could
be an arbitrary expression in terms of constants, functions, and other
variables, e.g.@: @math{(@var{var1} + @var{var2}) / 2}.  In practice,
the corpus contains only the following forms of expressions:

@table @code
@item constant(0)
@itemx constant(@var{variable})
All zeros.  The reason why a variable is sometimes named is unknown.
Sometimes the ``variable name'' has spaces in it.

@item map(@var{variable})
Transforms the values in the named @var{variable} using the
@code{valueMapEntry}s contained within the element.
@end table
@end defvr

@defvr {Attribute} dependsOn
This attribute doesn't affect the display of a table.
@end defvr

@node SPV Detail valueMapEntry Element
@subsubsection The @code{valueMapEntry} Element

@example
valueMapEntry :from :to => EMPTY
@end example

A @code{valueMapEntry} element defines a mapping from one or more
values of a source expression to a target value.  (In the corpus, the
source expression is always just the name of a variable.)  Each target
value requires a separate @code{valueMapEntry}.  If multiple source
values map to the same target value, they can be combined or separate.

In the corpus, all of the source and target values are integers.

@code{valueMapEntry} has the following attributes.

@defvr {Attribute} from
A source value, or multiple source values separated by semicolons,
e.g.@: @code{0} or @code{13;14;15;16}.
@end defvr

@defvr {Attribute} to
The target value, e.g.@: @code{0}.
@end defvr

@node SPV Detail extension Element
@subsection The @code{extension} Element

This is a general-purpose ``extension'' element.  Readers that don't
understand a given extension should be able to safely ignore it.  The
attributes on this element, and their meanings, vary based on the
context.  Each known usage is described separately below.  The current
extensions use attributes exclusively, without any nested elements.

@subsubheading @code{container} Parent Element

@example
extension[container_extension] :combinedFootnotes=(true) => EMPTY
@end example

With @code{container} as its parent element, @code{extension} has the
following attributes.

@defvr {Attribute} combinedFootnotes
Always set to @code{true} in the corpus.
@end defvr

@subsubheading @code{sourceVariable} and @code{derivedVariable} Parent Element

@example
extension[variable_extension] :from :helpId => EMPTY
@end example

With @code{sourceVariable} or @code{derivedVariable} as its parent
element, @code{extension} has the following attributes.  A given
parent element often contains several @code{extension} elements that
specify the meaning of the source data's variables or sources, e.g.@:

@example
<extension from="0" helpId="corrected_model"/>
<extension from="3" helpId="error"/>
<extension from="4" helpId="total_9"/>
<extension from="5" helpId="corrected_total"/>
@end example

More commonly they are less helpful, e.g.@:

@example
<extension from="0" helpId="notes"/>
<extension from="1" helpId="notes"/>
<extension from="2" helpId="notes"/>
<extension from="5" helpId="notes"/>
<extension from="6" helpId="notes"/>
<extension from="7" helpId="notes"/>
<extension from="8" helpId="notes"/>
<extension from="12" helpId="notes"/>
<extension from="13" helpId="no_help"/>
<extension from="14" helpId="notes"/>
@end example

@defvr {Attribute} from
An integer or a name like ``dimension0''.
@end defvr

@defvr {Attribute} helpId
An identifier.
@end defvr

@node SPV Detail graph Element
@subsection The @code{graph} Element

@example
graph
   :cellStyle=ref style
   :style=ref style
=> location+ coordinates faceting facetLayout interval

coordinates => EMPTY
@end example

@code{graph} has the following attributes.

@defvr {Attribute} cellStyle
@defvrx {Attribute} style
Each of these is the @code{id} of a @code{style} element (@pxref{SPV
Detail style Element}).  The former is the default style for
individual cells, the latter for the entire table.
@end defvr

@node SPV Detail location Element
@subsection The @code{location} Element

@example
location
   :part=(height | width | top | bottom | left | right)
   :method=(sizeToContent | attach | fixed | same)
   :min=dimension?
   :max=dimension?
   :target=ref (labelFrame | graph | container)?
   :value?
=> EMPTY
@end example

Each instance of this element specifies where some part of the table
frame is located.  All the examples in the corpus have four instances
of this element, one for each of the parts @code{height},
@code{width}, @code{left}, and @code{top}.  Some examples in the
corpus add a fifth for part @code{bottom}, even though it is not clear
how all of @code{top}, @code{bottom}, and @code{height} can be honored
at the same time.  In any case, @code{location} seems to have little
importance in representing tables; a reader can safely ignore it.

@defvr {Attribute} part
The part of the table being located.
@end defvr

@defvr {Attribute} method
How the location is determined:

@table @code
@item sizeToContent
Based on the natural size of the table.  Observed only for
parts @code{height} and @code{width}.

@item attach
Based on the location specified in @code{target}.  Observed only for
parts @code{top} and @code{bottom}.

@item fixed
Using the value in @code{value}.  Observed only for parts @code{top},
@code{bottom}, and @code{left}.

@item same
Same as the specified @code{target}.  Observed only for part
@code{left}.
@end table
@end defvr

@defvr {Attribute} min
Minimum size.  Only observed with value @code{100pt}.  Only observed
for part @code{width}.
@end defvr

@defvr {Dependent} target
Required when @code{method} is @code{attach} or @code{same}, not
observed otherwise.  This identifies an element to attach to.
Observed with the ID of @code{title}, @code{footnote}, @code{graph},
and other elements.
@end defvr

@defvr {Dependent} value
Required when @code{method} is @code{fixed}, not observed otherwise.
Observed values are @code{0%}, @code{0px}, @code{1px}, and @code{3px}
on parts @code{top} and @code{left}, and @code{100%} on part
@code{bottom}.
@end defvr

@node SPV Detail faceting Element
@subsection The @code{faceting} Element

@example
faceting => layer[layers1]* cross layer[layers2]*

cross => (unity | nest) (unity | nest)

unity => EMPTY

nest => variableReference[vars]+

variableReference :ref=ref (sourceVariable | derivedVariable) => EMPTY

layer
   :variable=ref (sourceVariable | derivedVariable)
   :value
   :visible=bool?
   :method[layer_method]=(nest)?
   :titleVisible=bool?
=> EMPTY
@end example

The @code{faceting} element describes the row, column, and layer
structure of the table.  Its @code{cross} child determines the row and
column structure, and each @code{layer} child (if any) represents a
layer.  Layers may appear before or after @code{cross}.

The @code{cross} element describes the row and column structure of the
table.  It has exactly two children, the first of which describes the
table's columns and the second the table's rows.  Each child is a
@code{nest} element if the table has any dimensions along the axis in
question, otherwise a @code{unity} element.

A @code{nest} element contains of one or more dimensions listed from
innermost to outermost, each represented by @code{variableReference}
child elements.  Each variable in a dimension is listed in order.
@xref{SPV Detail Variable Elements}, for information on the variables
that comprise a dimension.

A @code{nest} can contain a single dimension, e.g.:

@example
<nest>
  <variableReference ref="dimension0categories"/>
  <variableReference ref="dimension0group0"/>
  <variableReference ref="dimension0"/>
</nest>
@end example

@noindent
A @code{nest} can contain multiple dimensions, e.g.:

@example
<nest>
  <variableReference ref="dimension1categories"/>
  <variableReference ref="dimension1group0"/>
  <variableReference ref="dimension1"/>
  <variableReference ref="dimension0categories"/>
  <variableReference ref="dimension0"/>
</nest>
@end example

A @code{nest} may have no dimensions, in which case it still has one
@code{variableReference} child, which references a
@code{derivedVariable} whose @code{value} attribute is
@code{constant(0)}.  In the corpus, such a @code{derivedVariable} has
@code{row} or @code{column}, respectively, as its @code{id}.  This is
equivalent to using a @code{unity} element in place of @code{nest}.

A @code{variableReference} element refers to a variable through its
@code{ref} attribute.

Each @code{layer} element represents a dimension, e.g.:

@example
<layer value="0" variable="dimension0categories" visible="true"/>
<layer value="dimension0" variable="dimension0" visible="false"/>
@end example

@noindent
@code{layer} has the following attributes.

@defvr {Attribute} variable
Refers to a @code{sourceVariable} or @code{derivedVariable} element.
@end defvr

@defvr {Attribute} value
The value to select.  For a category variable, this is always
@code{0}; for a data variable, it is the same as the @code{variable}
attribute.
@end defvr

@defvr {Attribute} visible
Whether the layer is visible.  Generally, category layers are visible
and data layers are not, but sometimes this attribute is omitted.
@end defvr

@defvr {Attribute} method
When present, this is always @code{nest}.
@end defvr

@node SPV Detail facetLayout Element
@subsection The @code{facetLayout} Element

@example
facetLayout => tableLayout setCellProperties[scp1]*
               facetLevel+ setCellProperties[scp2]*

tableLayout
   :verticalTitlesInCorner=bool
   :style=ref style?
   :fitCells=(ticks both)?
=> EMPTY
@end example

The @code{facetLayout} element and its descendants control styling for
the table.

Its @code{tableLayout} child has the following attributes

@defvr {Attribute} verticalTitlesInCorner
If true, in the absence of corner text, row headings will be displayed
in the corner.
@end defvr

@defvr {Attribute} style
Refers to a @code{style} element.
@end defvr

@defvr {Attribute} fitCells
Meaning unknown.
@end defvr

@subsubheading The @code{facetLevel} Element

@example
facetLevel :level=int :gap=dimension? => axis

axis :style=ref style => label? majorTicks

majorTicks
   :labelAngle=int
   :length=dimension
   :style=ref style
   :tickFrameStyle=ref style
   :labelFrequency=int?
   :stagger=bool?
=> gridline?

gridline
   :style=ref style
   :zOrder=int
=> EMPTY
@end example

Each @code{facetLevel} describes a @code{variableReference} or
@code{layer}, and a table has one @code{facetLevel} element for
each such element.  For example, an SPV detail member that contains
four @code{variableReference} elements and two @code{layer} elements
will contain six @code{facetLevel} elements.

In the corpus, @code{facetLevel} elements and the elements that they
describe are always in the same order.  The correspondence may also be
observed in two other ways.  First, one may use the @code{level}
attribute, described below.  Second, in the corpus, a
@code{facetLevel} always has an @code{id} that is the same as the
@code{id} of the element it describes with @code{_facetLevel}
appended.  One should not formally rely on this, of course, but it is
usefully indicative.

@defvr {Attribute} level
A 1-based index into the @code{variableReference} and @code{layer}
elements, e.g.@: a @code{facetLayout} with a @code{level} of 1
describes the first @code{variableReference} in the SPV detail member,
and in a member with four @code{variableReference} elements, a
@code{facetLayout} with a @code{level} of 5 describes the first
@code{layer} in the member.
@end defvr

@defvr {Attribute} gap
Always observed as @code{0pt}.
@end defvr

Each @code{facetLevel} contains an @code{axis}, which in turn may
contain a @code{label} for the @code{facetLevel} (@pxref{SPV Detail
label Element}) and does contain a @code{majorTicks} element.

@defvr {Attribute} labelAngle
Normally 0.  The value -90 causes inner column or outer row labels to
be rotated vertically.
@end defvr

@defvr {Attribute} style
@defvrx {Attribute} tickFrameStyle
Each refers to a @code{style} element.  @code{style} is the style of
the tick labels, @code{tickFrameStyle} the style for the frames around
the labels.
@end defvr

@node SPV Detail label Element
@subsection The @code{label} Element

@example
label
   :style=ref style
   :textFrameStyle=ref style?
   :purpose=(title | subTitle | subSubTitle | layer | footnote)?
=> text+ | descriptionGroup

descriptionGroup
   :target=ref faceting
   :separator?
=> (description | text)+

description :name=(variable | value) => EMPTY

text
   :usesReference=int?
   :definesReference=int?
   :position=(subscript | superscript)?
   :style=ref style
=> TEXT
@end example

This element represents a label on some aspect of the table.

@defvr {Attribute} style
@defvrx {Attribute} textFrameStyle
Each of these refers to a @code{style} element.  @code{style} is the
style of the label text, @code{textFrameStyle} the style for the frame
around the label.
@end defvr

@defvr {Attribute} purpose
The kind of entity being labeled.
@end defvr

A @code{descriptionGroup} concatenates one or more elements to form a
label.  Each element can be a @code{text} element, which contains
literal text, or a @code{description} element that substitutes a value
or a variable name.

@defvr {Attribute} target
The @code{id} of an element being described.  In the corpus, this is
always @code{faceting}.
@end defvr

@defvr {Attribute} separator
A string to separate the description of multiple groups, if the
@code{target} has more than one.  In the corpus, this is always a
new-line.
@end defvr

Typical contents for a @code{descriptionGroup} are a value by itself:
@example
<description name="value"/>
@end example
@noindent or a variable and its value, separated by a colon:
@example
<description name="variable"/><text>:</text><description name="value"/>
@end example

A @code{description} is like a macro that expands to some property of
the target of its parent @code{descriptionGroup}.  The @code{name}
attribute specifies the property.

@node SPV Detail setCellProperties Element
@subsection The @code{setCellProperties} Element

@example
setCellProperties
   :applyToConverse=bool?
=> (setStyle | setFrameStyle | setFormat | setMetaData)* union[union_]?
@end example

The @code{setCellProperties} element sets style properties of cells or
row or column labels.

Interpreting @code{setCellProperties} requires answering two
questions: which cells or labels to style, and what styles to use.

@subsubheading Which Cells?

@example
union => intersect+

intersect => where+ | intersectWhere | alternating | EMPTY

where
   :variable=ref (sourceVariable | derivedVariable)
   :include
=> EMPTY

intersectWhere
   :variable=ref (sourceVariable | derivedVariable)
   :variable2=ref (sourceVariable | derivedVariable)
=> EMPTY

alternating => EMPTY
@end example

When @code{union} is present with @code{intersect} children, each of
those children specifies a group of cells that should be styled, and
the total group is all those cells taken together.  When @code{union}
is absent, every cell is styled.  One attribute on
@code{setCellProperties} affects the choice of cells:

@defvr {Attribute} applyToConverse
If true, this inverts the meaning of the cell selection: the selected
cells are the ones @emph{not} designated.  This is confusing, given
the additional restrictions of @code{union}, but in the corpus
@code{applyToConverse} is never present along with @code{union}.
@end defvr

An @code{intersect} specifies restrictions on the cells to be matched.
Each @code{where} child specifies which values of a given variable to
include.  The attributes of @code{intersect} are:

@defvr {Attribute} variable
Refers to a variable, e.g.@: @code{dimension0categories}.  Only
``categories'' variables make sense here, but other variables, e.g.@:
@code{dimension0group0map}, are sometimes seen.  The reader may ignore
these.
@end defvr

@defvr {Attribute} include
A value, or multiple values separated by semicolons,
e.g.@: @code{0} or @code{13;14;15;16}.
@end defvr

PSPP ignores @code{setCellProperties} when @code{intersectWhere} is
present.

@subsubheading What Styles?

@example
setStyle
   :target=ref (labeling | graph | interval | majorTicks)
   :style=ref style
=> EMPTY

setMetaData :target=ref graph :key :value => EMPTY

setFormat
   :target=ref (majorTicks | labeling)
   :reset=bool?
=> format | numberFormat | stringFormat+ | dateTimeFormat | elapsedTimeFormat

setFrameStyle
   :style=ref style
   :target=ref majorTicks
=> EMPTY
@end example

The @code{set*} children of @code{setCellProperties} determine the
styles to set.

When @code{setCellProperties} contains a @code{setFormat} whose
@code{target} references a @code{labeling} element, or if it contains
a @code{setStyle} that references a @code{labeling} or @code{interval}
element, the @code{setCellProperties} sets the style for table cells.
The format from the @code{setFormat}, if present, replaces the cells'
format.  The style from the @code{setStyle} that references
@code{labeling}, if present, replaces the label's font and cell
styles, except that the background color is taken instead from the
@code{interval}'s style, if present.

When @code{setCellProperties} contains a @code{setFormat} whose
@code{target} references a @code{majorTicks} element, or if it
contains a @code{setStyle} whose @code{target} references a
@code{majorTicks}, or if it contains a @code{setFrameStyle} element,
the @code{setCellProperties} sets the style for row or column labels.
In this case, the @code{setCellProperties} always contains a single
@code{where} element whose @code{variable} designates the variable
whose labels are to be styled.  The format from the @code{setFormat},
if present, replaces the labels' format.  The style from the
@code{setStyle} that references @code{majorTicks}, if present,
replaces the labels' font and cell styles, except that the background
color is taken instead from the @code{setFrameStyle}'s style, if
present.

When @code{setCellProperties} contains a @code{setStyle} whose
@code{target} references a @code{graph} element, and one that
references a @code{labeling} element, and the @code{union} element
contains @code{alternating}, the @code{setCellProperties} sets the
alternate foreground and background colors for the data area.  The
foreground color is taken from the style referenced by the
@code{setStyle} that targets the @code{graph}, the background color
from the @code{setStyle} for @code{labeling}.

A reader may ignore a @code{setCellProperties} that only contains
@code{setMetaData}, as well as @code{setMetaData} within other
@code{setCellProperties}.

A reader may ignore a @code{setCellProperties} whose only @code{set*}
child is a @code{setStyle} that targets the @code{graph} element.

@subsubheading The @code{setStyle} Element

@example
setStyle
   :target=ref (labeling | graph | interval | majorTicks)
   :style=ref style
=> EMPTY
@end example

This element associates a style with the target.

@defvr {Attribute} target
The @code{id} of an element whose style is to be set.
@end defvr

@defvr {Attribute} style
The @code{id} of a @code{style} element that identifies the style to
set on the target.
@end defvr

@node SPV Detail setFormat Element
@subsection The @code{setFormat} Element

@example
setFormat
   :target=ref (majorTicks | labeling)
   :reset=bool?
=> format | numberFormat | stringFormat+ | dateTimeFormat | elapsedTimeFormat
@end example

This element sets the format of the target, ``format'' in this case
meaning the SPSS print format for a variable.

The details of this element vary depending on the schema version, as
declared in the root @code{visualization} element's @code{version}
attribute (@pxref{SPV Detail visualization Element}).  A reader can
interpret the content without knowing the schema version.

The @code{setFormat} element itself has the following attributes.

@defvr {Attribute} target
Refers to an element whose style is to be set.
@end defvr

@defvr {Attribute} reset
If this is @code{true}, this format replaces the target's previous
format.  If it is @code{false}, the modifies the previous format.
@end defvr

@menu
* SPV Detail numberFormat Element::
* SPV Detail stringFormat Element::
* SPV Detail dateTimeFormat Element::
* SPV Detail elapsedTimeFormat Element::
* SPV Detail format Element::
* SPV Detail affix Element::
@end menu

@node SPV Detail numberFormat Element
@subsubsection The @code{numberFormat} Element

@example
numberFormat
   :minimumIntegerDigits=int?
   :maximumFractionDigits=int?
   :minimumFractionDigits=int?
   :useGrouping=bool?
   :scientific=(onlyForSmall | whenNeeded | true | false)?
   :small=real?
   :prefix?
   :suffix?
=> affix*
@end example

Specifies a format for displaying a number.  The available options are
a superset of those available from PSPP print formats.  PSPP chooses a
print format type for a @code{numberFormat} as follows:

@enumerate
@item
If @code{scientific} is @code{true}, uses @code{E} format.

@item
If @code{prefix} is @code{$}, uses @code{DOLLAR} format.

@item
If @code{suffix} is @code{%}, uses @code{PCT} format.

@item
If @code{useGrouping} is @code{true}, uses @code{COMMA} format.

@item
Otherwise, uses @code{F} format.
@end enumerate

For translating to a print format, PSPP uses
@code{maximumFractionDigits} as the number of decimals, unless that
attribute is missing or out of the range [0,15], in which case it uses
2 decimals.

@defvr {Attribute} minimumIntegerDigits
Minimum number of digits to display before the decimal point.  Always
observed as @code{0}.
@end defvr

@defvr {Attribute} maximumFractionDigits
@defvrx {Attribute} minimumFractionDigits
Maximum or minimum, respectively, number of digits to display after
the decimal point.  The observed values of each attribute range from 0
to 9.
@end defvr

@defvr {Attribute} useGrouping
Whether to use the grouping character to group digits in large
numbers.
@end defvr

@defvr {Attribute} scientific
This attribute controls when and whether the number is formatted in
scientific notation.  It takes the following values:

@table @code
@item onlyForSmall
Use scientific notation only when the number's magnitude is smaller
than the value of the @code{small} attribute.

@item whenNeeded
Use scientific notation when the number will not otherwise fit in the
available space.

@item true
Always use scientific notation.  Not observed in the corpus.

@item false
Never use scientific notation.  A number that won't otherwise fit will
be replaced by an error indication (see the @code{errorCharacter}
attribute).  Not observed in the corpus.
@end table
@end defvr

@defvr {Attribute} small
Only present when the @code{scientific} attribute is
@code{onlyForSmall}, this is a numeric magnitude below which the
number will be formatted in scientific notation.  The values @code{0}
and @code{0.0001} have been observed.  The value @code{0} seems like a
pathological choice, since no real number has a magnitude less than 0;
perhaps in practice such a choice is equivalent to setting
@code{scientific} to @code{false}.
@end defvr

@defvr {Attribute} prefix
@defvrx {Attribute} suffix
Specifies a prefix or a suffix to apply to the formatted number.  Only
@code{suffix} has been observed, with value @samp{%}.
@end defvr

@node SPV Detail stringFormat Element
@subsubsection The @code{stringFormat} Element

@example
stringFormat => relabel* affix*

relabel :from=real :to => EMPTY
@end example

The @code{stringFormat} element specifies how to display a string.  By
default, a string is displayed verbatim, but @code{relabel} can change
it.

The @code{relabel} element appears as a child of @code{stringFormat}
(and of @code{format}, when it is used to format strings).  It
specifies how to display a given value.  It is used to implement value
labels and to display the system-missing value in a human-readable
way.  It has the following attributes:

@defvr {Attribute} from
The value to map.  In the corpus this is an integer or the
system-missing value @code{-1.797693134862316E300}.
@end defvr

@defvr {Attribute} to
The string to display in place of the value of @code{from}.  In the
corpus this is a wide variety of value labels; the system-missing
value is mapped to @samp{.}.
@end defvr

@node SPV Detail dateTimeFormat Element
@subsubsection The @code{dateTimeFormat} Element

@example
dateTimeFormat
   :baseFormat[dt_base_format]=(date | time | dateTime)
   :separatorChars?
   :mdyOrder=(dayMonthYear | monthDayYear | yearMonthDay)?
   :showYear=bool?
   :yearAbbreviation=bool?
   :showQuarter=bool?
   :quarterPrefix?
   :quarterSuffix?
   :showMonth=bool?
   :monthFormat=(long | short | number | paddedNumber)?
   :showWeek=bool?
   :weekPadding=bool?
   :weekSuffix?
   :showDayOfWeek=bool?
   :dayOfWeekAbbreviation=bool?
   :dayPadding=bool?
   :dayOfMonthPadding=bool?
   :hourPadding=bool?
   :minutePadding=bool?
   :secondPadding=bool?
   :showDay=bool?
   :showHour=bool?
   :showMinute=bool?
   :showSecond=bool?
   :showMillis=bool?
   :dayType=(month | year)?
   :hourFormat=(AMPM | AS_24 | AS_12)?
=> affix*
@end example

This element appears only in schema version 2.5 and earlier
(@pxref{SPV Detail visualization Element}).

Data to be formatted in date formats is stored as strings in legacy
data, in the format @code{yyyy-mm-ddTHH:MM:SS.SSS} and must be parsed
and reformatted by the reader.

The following attribute is required.

@defvr {Attribute} baseFormat
Specifies whether a date and time are both to be displayed, or just
one of them.
@end defvr

Many of the attributes' meanings are obvious.  The following seem to
be worth documenting.

@defvr {Attribute} separatorChars
Exactly four characters.  In order, these are used for: decimal point,
grouping, date separator, time separator.  Always @samp{.,-:}.
@end defvr

@defvr {Attribute} mdyOrder
Within a date, the order of the days, months, and years.
@code{dayMonthYear} is the only observed value, but one would expect
that @code{monthDayYear} and @code{yearMonthDay} to be reasonable as
well.
@end defvr

@defvr {Attribute} showYear
@defvrx {Attribute} yearAbbreviation
Whether to include the year and, if so, whether the year should be
shown abbreviated, that is, with only 2 digits.  Each is @code{true}
or @code{false}; only values of @code{true} and @code{false},
respectively, have been observed.
@end defvr

@defvr {Attribute} showMonth
@defvrx {Attribute} monthFormat
Whether to include the month (@code{true} or @code{false}) and, if so,
how to format it.  @code{monthFormat} is one of the following:

@table @code
@item long
The full name of the month, e.g.@: in an English locale,
@code{September}.

@item short
The abbreviated name of the month, e.g.@: in an English locale,
@code{Sep}.

@item number
The number representing the month, e.g.@: 9 for September.

@item paddedNumber
A two-digit number representing the month, e.g.@: 09 for September.
@end table

Only values of @code{true} and @code{short}, respectively, have been
observed.
@end defvr

@defvr {Attribute} dayType
This attribute is always @code{month} in the corpus, specifying that
the day of the month is to be displayed; a value of @code{year} is
supposed to indicate that the day of the year, where 1 is January 1,
is to be displayed instead.
@end defvr

@defvr {Attribute} hourFormat
@code{hourFormat}, if present, is one of:

@table @code
@item AMPM
The time is displayed with an @code{am} or @code{pm} suffix, e.g.@:
@code{10:15pm}.

@item AS_24
The time is displayed in a 24-hour format, e.g.@: @code{22:15}.

This is the only value observed in the corpus.

@item AS_12
The time is displayed in a 12-hour format, without distinguishing
morning or evening, e.g.@: @code{10;15}.
@end table

@code{hourFormat} is sometimes present for @code{elapsedTime} formats,
which is confusing since a time duration does not have a concept of AM
or PM.  This might indicate a bug in the code that generated the XML
in the corpus, or it might indicate that @code{elapsedTime} is
sometimes used to format a time of day.
@end defvr

For a @code{baseFormat} of @code{date}, PSPP chooses a print format
type based on the following rules:

@enumerate
@item
If @code{showQuarter} is true: @code{QYR}.

@item
Otherwise, if @code{showWeek} is true: @code{WKYR}.

@item
Otherwise, if @code{mdyOrder} is @code{dayMonthYear}:

@enumerate a
@item
If @code{monthFormat} is @code{number} or @code{paddedNumber}: @code{EDATE}.

@item
Otherwise: @code{DATE}.
@end enumerate

@item
Otherwise, if @code{mdyOrder} is @code{yearMonthDay}: @code{SDATE}.

@item
Otherwise, @code{ADATE}.
@end enumerate

For a @code{baseFormat} of @code{dateTime}, PSPP uses @code{YMDHMS} if
@code{mdyOrder} is @code{yearMonthDay} and @code{DATETIME} otherwise.
For a @code{baseFormat} of @code{time}, PSPP uses @code{DTIME} if
@code{showDay} is true, otherwise @code{TIME} if @code{showHour} is
true, otherwise @code{MTIME}.

For a @code{baseFormat} of @code{date}, the chosen width is the
minimum for the format type, adding 2 if @code{yearAbbreviation} is
false or omitted.  For other base formats, the chosen width is the
minimum for its type, plus 3 if @code{showSecond} is true, plus 4 more
if @code{showMillis} is also true.  Decimals are 0 by default, or 3
if @code{showMillis} is true.

@node SPV Detail elapsedTimeFormat Element
@subsubsection The @code{elapsedTimeFormat} Element

@example
elapsedTimeFormat
   :baseFormat[dt_base_format]=(date | time | dateTime)
   :dayPadding=bool?
   :hourPadding=bool?
   :minutePadding=bool?
   :secondPadding=bool?
   :showYear=bool?
   :showDay=bool?
   :showHour=bool?
   :showMinute=bool?
   :showSecond=bool?
   :showMillis=bool?
=> affix*
@end example

This element specifies the way to display a time duration.

Data to be formatted in elapsed time formats is stored as strings in
legacy data, in the format @code{H:MM:SS.SSS}, with additional hour
digits as needed for long durations, and must be parsed and
reformatted by the reader.

The following attribute is required.

@defvr {Attribute} baseFormat
Specifies whether a day and a time are both to be displayed, or just
one of them.
@end defvr

The remaining attributes specify exactly how to display the elapsed
time.

For @code{baseFormat} of @code{time}, PSPP converts this element to
print format type @code{DTIME}; otherwise, if @code{showHour} is true,
to @code{TIME}; otherwise, to @code{MTIME}.  The chosen width is the
minimum for the chosen type, adding 3 if @code{showSecond} is true,
adding 4 more if @code{showMillis} is also true.  Decimals are 0 by
default, or 3 if @code{showMillis} is true.

@node SPV Detail format Element
@subsubsection The @code{format} Element

@example
format
   :baseFormat[f_base_format]=(date | time | dateTime | elapsedTime)?
   :errorCharacter?
   :separatorChars?
   :mdyOrder=(dayMonthYear | monthDayYear | yearMonthDay)?
   :showYear=bool?
   :showQuarter=bool?
   :quarterPrefix?
   :quarterSuffix?
   :yearAbbreviation=bool?
   :showMonth=bool?
   :monthFormat=(long | short | number | paddedNumber)?
   :dayPadding=bool?
   :dayOfMonthPadding=bool?
   :showWeek=bool?
   :weekPadding=bool?
   :weekSuffix?
   :showDayOfWeek=bool?
   :dayOfWeekAbbreviation=bool?
   :hourPadding=bool?
   :minutePadding=bool?
   :secondPadding=bool?
   :showDay=bool?
   :showHour=bool?
   :showMinute=bool?
   :showSecond=bool?
   :showMillis=bool?
   :dayType=(month | year)?
   :hourFormat=(AMPM | AS_24 | AS_12)?
   :minimumIntegerDigits=int?
   :maximumFractionDigits=int?
   :minimumFractionDigits=int?
   :useGrouping=bool?
   :scientific=(onlyForSmall | whenNeeded | true | false)?
   :small=real?
   :prefix?
   :suffix?
   :tryStringsAsNumbers=bool?
   :negativesOutside=bool?
=> relabel* affix*
@end example

This element is the union of all of the more-specific format elements.
It is interpreted in the same way as one of those format elements,
using @code{baseFormat} to determine which kind of format to use.

There are a few attributes not present in the more specific formats:

@defvr {Attribute} tryStringsAsNumbers
When this is @code{true}, it is supposed to indicate that string
values should be parsed as numbers and then displayed according to
numeric formatting rules.  However, in the corpus it is always
@code{false}.
@end defvr

@defvr {Attribute} negativesOutside
If true, the negative sign should be shown before the prefix; if
false, it should be shown after.
@end defvr

@node SPV Detail affix Element
@subsubsection The @code{affix} Element

@example
affix
   :definesReference=int
   :position=(subscript | superscript)
   :suffix=bool
   :value
=> EMPTY
@end example

This defines a suffix (or, theoretically, a prefix) for a formatted
value.  It is used to insert a reference to a footnote.  It has the
following attributes:

@defvr {Attribute} definesReference
This specifies the footnote number as a natural number: 1 for the
first footnote, 2 for the second, and so on.
@end defvr

@defvr {Attribute} position
Position for the footnote label.  Always @code{superscript}.
@end defvr

@defvr {Attribute} suffix
Whether the affix is a suffix (@code{true}) or a prefix
(@code{false}).  Always @code{true}.
@end defvr

@defvr {Attribute} value
The text of the suffix or prefix.  Typically a letter, e.g.@: @code{a}
for footnote 1, @code{b} for footnote 2, @enddots{}  The corpus
contains other values: @code{*}, @code{**}, and a few that begin with
at least one comma: @code{,b}, @code{,c}, @code{,,b}, and @code{,,c}.
@end defvr

@node SPV Detail interval Element
@subsection The @code{interval} Element

@example
interval :style=ref style => labeling footnotes?

labeling
   :style=ref style?
   :variable=ref (sourceVariable | derivedVariable)
=> (formatting | format | footnotes)*

formatting :variable=ref (sourceVariable | derivedVariable) => formatMapping*

formatMapping :from=int => format?

footnotes
   :superscript=bool?
   :variable=ref (sourceVariable | derivedVariable)
=> footnoteMapping*

footnoteMapping :definesReference=int :from=int :to => EMPTY
@end example

The @code{interval} element and its descendants determine the basic
formatting and labeling for the table's cells.  These basic styles are
overridden by more specific styles set using @code{setCellProperties}
(@pxref{SPV Detail setCellProperties Element}).

The @code{style} attribute of @code{interval} itself may be ignored.

The @code{labeling} element may have a single @code{formatting} child.
If present, its @code{variable} attribute refers to a variable whose
values are format specifiers as numbers, e.g. value 0x050802 for F8.2.
However, the numbers are not actually interpreted that way.  Instead,
each number actually present in the variable's data is mapped by a
@code{formatMapping} child of @code{formatting} to a @code{format}
that specifies how to display it.

The @code{labeling} element may also have a @code{footnotes} child
element.  The @code{variable} attribute of this element refers to a
variable whose values are comma-delimited strings that list the
1-based indexes of footnote references.  (Cells without any footnote
references are numeric 0 instead of strings.)

Each @code{footnoteMapping} child of the @code{footnotes} element
defines the footnote marker to be its @code{to} attribute text for the
footnote whose 1-based index is given in its @code{definesReference}
attribute.

@node SPV Detail style Element
@subsection The @code{style} Element

@example
style
   :color=color?
   :color2=color?
   :labelAngle=real?
   :border-bottom=(solid | thick | thin | double | none)?
   :border-top=(solid | thick | thin | double | none)?
   :border-left=(solid | thick | thin | double | none)?
   :border-right=(solid | thick | thin | double | none)?
   :border-bottom-color?
   :border-top-color?
   :border-left-color?
   :border-right-color?
   :font-family?
   :font-size?
   :font-weight=(regular | bold)?
   :font-style=(regular | italic)?
   :font-underline=(none | underline)?
   :margin-bottom=dimension?
   :margin-left=dimension?
   :margin-right=dimension?
   :margin-top=dimension?
   :textAlignment=(left | right | center | decimal | mixed)?
   :labelLocationHorizontal=(positive | negative | center)?
   :labelLocationVertical=(positive | negative | center)?
   :decimal-offset=dimension?
   :size?
   :width?
   :visible=bool?
=> EMPTY
@end example

A @code{style} element has an effect only when it is referenced by
another element to set some aspect of the table's style.  Most of the
attributes are self-explanatory.  The rest are described below.

@defvr {Attribute} {color}
In some cases, the text color; in others, the background color.
@end defvr

@defvr {Attribute} {color2}
Not used.
@end defvr

@defvr {Attribute} {labelAngle}
Normally 0.  The value -90 causes inner column or outer row labels to
be rotated vertically.
@end defvr

@defvr {Attribute} {labelLocationHorizontal}
Not used.
@end defvr

@defvr {Attribute} {labelLocationVertical}
The value @code{positive} corresponds to vertically aligning text to
the top of a cell, @code{negative} to the bottom, @code{center} to the
middle.
@end defvr

@node SPV Detail labelFrame Element
@subsection The @code{labelFrame} Element

@example
labelFrame :style=ref style => location+ label? paragraph?

paragraph :hangingIndent=dimension? => EMPTY
@end example

A @code{labelFrame} element specifies content and style for some
aspect of a table.  Only @code{labelFrame} elements that have a
@code{label} child are important.  The @code{purpose} attribute in the
@code{label} determines what the @code{labelFrame} affects:

@table @code
@item title
The table's title and its style.

@item subTitle
The table's caption and its style.

@item footnote
The table's footnotes and the style for the footer area.

@item layer
The style for the layer area.

@item subSubTitle
Ignored.
@end table

The @code{style} attribute references the style to use for the area.

The @code{label}, if present, specifies the text to put into the title
or caption or footnotes.  For footnotes, the label has two @code{text}
children for every footnote, each of which has a @code{usesReference}
attribute identifying the 1-based index of a footnote.  The first,
third, fifth, @dots{} @code{text} child specifies the content for a
footnote; the second, fourth, sixth, @dots{} child specifies the
marker.  Content tends to end in a new-line, which the reader may wish
to trim; similarly, markers tend to end in @samp{.}.

The @code{paragraph}, if present, may be ignored, since it is always
empty.

@node SPV Detail Legacy Properties
@subsection Legacy Properties

The detail XML format has features for styling most of the aspects of
a table.  It also inherits defaults for many aspects from structure
XML, which has the following @code{tableProperties} element:

@example
tableProperties
   :name?
=> generalProperties footnoteProperties cellFormatProperties borderProperties printingProperties

generalProperties
   :hideEmptyRows=bool?
   :maximumColumnWidth=dimension?
   :maximumRowWidth=dimension?
   :minimumColumnWidth=dimension?
   :minimumRowWidth=dimension?
   :rowDimensionLabels=(inCorner | nested)?
=> EMPTY

footnoteProperties
   :markerPosition=(superscript | subscript)?
   :numberFormat=(alphabetic | numeric)?
=> EMPTY

cellFormatProperties => cell_style+

any[cell_style]
   :alternatingColor=color?
   :alternatingTextColor=color?
=> style

style
   :color=color?
   :color2=color?
   :font-family?
   :font-size?
   :font-style=(regular | italic)?
   :font-weight=(regular | bold)?
   :font-underline=(none | underline)?
   :labelLocationVertical=(positive | negative | center)?
   :margin-bottom=dimension?
   :margin-left=dimension?
   :margin-right=dimension?
   :margin-top=dimension?
   :textAlignment=(left | right | center | decimal | mixed)?
   :decimal-offset=dimension?
=> EMPTY

borderProperties => border_style+

any[border_style]
   :borderStyleType=(none | solid | dashed | thick | thin | double)?
   :color=color?
=> EMPTY

printingProperties
   :printAllLayers=bool?
   :rescaleLongTableToFitPage=bool?
   :rescaleWideTableToFitPage=bool?
   :windowOrphanLines=int?
   :continuationText?
   :continuationTextAtBottom=bool?
   :continuationTextAtTop=bool?
   :printEachLayerOnSeparatePage=bool?
=> EMPTY
@end example

The @code{name} attribute appears only in standalone @file{.stt} files
(@pxref{SPSS TableLook STT Format}).