* Document Record::
* Machine Integer Info Record::
* Machine Floating-Point Info Record::
+* Multiple Response Sets Records::
* Variable Display Parameter Record::
* Long Variable Names Record::
* Very Long String Record::
@item int32 label_len;
This field is present only if @code{has_var_label} is set to 1. It is
-set to the length, in characters, of the variable label, which must be a
-number between 0 and 120.
+set to the length, in characters, of the variable label. The
+documented maximum length varies from 120 to 255 based on SPSS
+version, but some files have been seen with longer labels. PSPP
+accepts longer labels and truncates them to 255 bytes on input.
@item char label[];
This field is present only if @code{has_var_label} is set to 1. It has
following value label variables record (see below) is read.
@item char label_len;
-The label's length, in bytes.
+The label's length, in bytes. The documented maximum length varies
+from 60 to 120 based on SPSS version. PSPP supports value labels up
+to 255 bytes long.
@item char label[];
@code{label_len} bytes of the actual label, followed by up to 7 bytes
The value used for LOWEST in missing values.
@end table
+@node Multiple Response Sets Records
+@section Multiple Response Sets Records
+
+The system file format has two different types of records that
+represent multiple response sets (@pxref{MRSETS,,,pspp, PSPP Users
+Guide}). The first type of record describes multiple response sets
+that can be understood by SPSS before version 14. The second type of
+record, with a closely related format, is used for multiple dichotomy
+sets that use the CATEGORYLABELS=COUNTEDVALUES feature added in
+version 14.
+
+@example
+/* @r{Header.} */
+int32 rec_type;
+int32 subtype;
+int32 size;
+int32 count;
+
+/* @r{Exactly @code{count} bytes of data.} */
+char mrsets[];
+@end example
+
+@table @code
+@item int32 rec_type;
+Record type. Always set to 7.
+
+@item int32 subtype;
+Record subtype. Set to 7 for records that describe multiple response
+sets understood by SPSS before version 14, or to 19 for records that
+describe dichotomy sets that use the CATEGORYLABELS=COUNTEDVALUES
+feature added in version 14.
+
+@item int32 size;
+The size of each element in the @code{mrsets} member. Always set to 1.
+
+@item int32 count;
+The total number of bytes in @code{mrsets}.
+
+@item char mrsets[];
+A series of multiple response sets, each of which consists of the
+following:
+
+@itemize @bullet
+@item
+The set's name (an identifier that begins with @samp{$}).
+
+@item
+An equals sign (@samp{=}).
+
+@item
+@samp{C} for a multiple category set, @samp{D} for a multiple
+dichotomy set with CATEGORYLABELS=VARLABELS, or @samp{E} for a
+multiple dichotomy set with CATEGORYLABELS=COUNTEDVALUES.
+
+@item
+For a multiple dichotomy set with CATEGORYLABELS=COUNTEDVALUES, a
+space, followed by a number expressed as decimal digits, followed by a
+space. If LABELSOURCE=VARLABEL was specified on MRSETS, then the
+number is 11; otherwise it is 1.@footnote{This part of the format may
+not be fully understood, because only a single example of each
+possibility has been examined.}
+
+@item
+For either kind of multiple dichotomy set, the counted value, as a
+positive integer count specified as decimal digits, followed by a
+space, followed by as many string bytes as specified in the count. If
+the set contains numeric variables, the string consists of the counted
+integer value expressed as decimal digits. If the set contains string
+variables, the string contains the counted string value. Either way,
+the string may be padded on the right with spaces (older versions of
+SPSS seem to always pad to a width of 8 bytes; newer versions don't).
+
+@item
+A space.
+
+@item
+The multiple response set's label, using the same format as for the
+counted value for multiple dichotomy sets. A string of length 0 means
+that the set does not have a label. A string of length 0 is also
+written if LABELSOURCE=VARLABEL was specified.
+
+@item
+A space.
+
+@item
+The names of the variables in the set, each separated from the
+previous by a single space.
+
+@item
+A line feed (byte 0x0a).
+@end itemize
+@end table
+
+Example: Given appropriate variable definitions, consider the
+following MRSETS command:
+
+@example
+MRSETS /MCGROUP NAME=$a LABEL='my mcgroup' VARIABLES=a b c
+ /MDGROUP NAME=$b VARIABLES=g e f d VALUE=55
+ /MDGROUP NAME=$c LABEL='mdgroup #2' VARIABLES=h i j VALUE='Yes'
+ /MDGROUP NAME=$d LABEL='third mdgroup' CATEGORYLABELS=COUNTEDVALUES
+ VARIABLES=k l m VALUE=34
+ /MDGROUP NAME=$e CATEGORYLABELS=COUNTEDVALUES LABELSOURCE=VARLABEL
+ VARIABLES=n o p VALUE='choice'.
+@end example
+
+The above would generate the following multiple response set record of
+subtype 7:
+
+@example
+$a=C 10 my mcgroup a b c
+$b=D2 55 0 g e f d
+$c=D3 Yes 10 mdgroup #2 h i j
+@end example
+
+It would also generate the following multiple response set record with
+subtype 19:
+
+@example
+$d=E 1 2 34 13 third mdgroup k l m
+$e=E 11 6 choice 0 n o p
+@end example
+
@node Variable Display Parameter Record
@section Variable Display Parameter Record
Continuous Scale
@end table
-SPSS 14 sometimes writes a @code{measure} of 0. PSPP interprets this
-as nominal scale.
+SPSS 14 sometimes writes a @code{measure} of 0 for string variables.
+PSPP interprets this as nominal scale.
@item int32 width;
The width of the display column for the variable in characters.
In record type 18, this field contains a sequence of one or more
variable attribute sets. If more than one variable attribute set is
present, each one after the first is delimited from the previous by
-@code{/}. Each variable attribute set consists of a variable name,
+@code{/}. Each variable attribute set consists of a (potentially
+long) variable name,
followed by @code{:}, followed by an attribute set with the same
syntax as on record type 17.
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