sys-file-reader: Tolerate nominal case size of 0 without warning.

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

diff --git a/doc/dev/system-file-format.texi b/doc/dev/system-file-format.texi
index 7cc0342c4cd81e966f45abbeafb9c65a3d2cce60..e52b9571166a25b477a8f6263f34d0960b9f0423 100644 (file)
--- a/doc/dev/system-file-format.texi
+++ b/doc/dev/system-file-format.texi
@@ -232,8 +232,8 @@ file's integer endianness (@pxref{System File Format}).
 Number of data elements per case.  This is the number of variables,
 except that long string variables add extra data elements (one for every
 8 characters after the first 8).  However, string variables do not
-contribute to this value beyond the first 255 bytes.   Further, system
-files written by some systems set this value to -1.  In general, it is
+contribute to this value beyond the first 255 bytes.   Further, some
+software always writes -1 or 0 in this field.  In general, it is
 unsafe for systems reading system files to rely upon this value.
 
 @item int32 compression;
@@ -605,7 +605,10 @@ char                lines[][80];
 Record type.  Always set to 6.
 
 @item int32 n_lines;
-Number of lines of documents present.
+Number of lines of documents present.  This should be greater than
+zero, but the system file writer that identifies itself as
+@url{https://github.com/WizardMac/ReadStat} writes document records
+with zero @code{n_lines}.
 
 @item char lines[][80];
 Document lines.  The number of elements is defined by @code{n_lines}.