VARIABLE ROLE: Document the format and add a test.

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

diff --git a/doc/dev/system-file-format.texi b/doc/dev/system-file-format.texi
index 062738181baa6923144e5af332c59355e6ee3a17..9bb636144030ea83c595a2ebd48a099192a61003 100644 (file)
--- a/doc/dev/system-file-format.texi
+++ b/doc/dev/system-file-format.texi
@@ -831,8 +831,8 @@ Ordinal Scale
 Continuous Scale
 @end table
 
-SPSS 14 sometimes writes a @code{measure} of 0 for string variables.
-PSPP interprets this as nominal scale.
+SPSS sometimes writes a @code{measure} of 0.  PSPP interprets this as
+nominal scale.
 
 @item int32 width;
 The width of the display column for the variable in characters.
@@ -1189,6 +1189,32 @@ will contain a variable attribute record with the following contents:
 00000030  0a 29                                             |.)              |
 @end example
 
+@menu
+* Variable Roles::
+@end menu
+
+@node Variable Roles
+@subsection Variable Roles
+
+A variable's role is represented as an attribute named @code{$@@Role}.
+This attribute has a single element whose values and their meanings
+are:
+
+@table @code
+@item 0
+Input.  This, the default, is the most common role.
+@item 1
+Output.
+@item 2
+Both.
+@item 3
+None.
+@item 4
+Partition.
+@item 5
+Split.
+@end table
+
 @node Extended Number of Cases Record
 @section Extended Number of Cases Record