Allow variable labels longer than 255 bytes.

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

diff --git a/doc/dev/system-file-format.texi b/doc/dev/system-file-format.texi
index a480195857f8d027cc910d9c9ac76b6d6ff26fb7..0f0940b58f88a2bfe9d13c0678dc52343be14982 100644 (file)
--- a/doc/dev/system-file-format.texi
+++ b/doc/dev/system-file-format.texi
@@ -328,7 +328,7 @@ 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.  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.
+accepts labels of any length.
 
 @item char label[];
 This field is present only if @code{has_var_label} is set to 1.  It has
@@ -735,8 +735,8 @@ The size of each element in the @code{mrsets} member. Always set to 1.
 The total number of bytes in @code{mrsets}.
 
 @item char mrsets[];
-A series of multiple response sets, each of which consists of the
-following:
+Zero or more line feeds (byte 0x0a), followed by a series of multiple
+response sets, each of which consists of the following:
 
 @itemize @bullet
 @item
@@ -785,8 +785,15 @@ A space.
 The short names of the variables in the set, converted to lowercase,
 each separated from the previous by a single space.
 
+Even though a multiple response set must have at least two variables,
+some system files contain multiple response sets with no variables at
+all.  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?)
+
 @item
-A line feed (byte 0x0a).
+One line feed (byte 0x0a).  Sometimes multiple, even hundreds, of line
+feeds are present.
 @end itemize
 @end table