sys-file-reader: Avoid hanging forever if a system file has no variables.

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

diff --git a/doc/dev/system-file-format.texi b/doc/dev/system-file-format.texi
index d100aa9d24d59fcd6265e73e70310d6b556403f8..4eb061580db5878b467fdbf4f6608f61d114972b 100644 (file)
--- a/doc/dev/system-file-format.texi
+++ b/doc/dev/system-file-format.texi
@@ -262,6 +262,10 @@ wider than 255 bytes.  Such very long string variables are represented
 by a number of narrower string variables.  @xref{Very Long String
 Record}, for details.
 
+A system file should contain at least one variable and thus at least
+one variable record, but system files have been observed in the wild
+without any variables (thus, no data either).
+
 @example
 int32               rec_type;
 int32               type;