The system file format has two different types of records that represent multiple response sets (see MRSETS in 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.
/* Header. */ int32 rec_type; int32 subtype; int32 size; int32 count; /* Exactly
countbytes of data. */ char mrsets;
Record type. Always set to 7.
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.
The size of each element in the
mrsets member. Always set to 1.
The total number of bytes in
Zero or more line feeds (byte 0x0a), followed by a series of multiple response sets, each of which consists of the following:
Even though a multiple response set must have at least two variables, some system files contain multiple response sets with no variables or one variable. The source and meaning of these multiple response sets is unknown. (Perhaps they arise from creating a multiple response set then deleting all the variables that it contains?)
Example: Given appropriate variable definitions, consider the following MRSETS command:
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'.
The above would generate the following multiple response set record of subtype 7:
$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
It would also generate the following multiple response set record with subtype 19:
$d=E 1 2 34 13 third mdgroup k l m $e=E 11 6 choice 0 n o p
This part of the format may not be fully understood, because only a single example of each possibility has been examined.