sys-file-reader: Tolerate nonsensical opcodes in compressed data.

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

diff --git a/doc/dev/system-file-format.texi b/doc/dev/system-file-format.texi
index 70fa385c7525efea051a5bfb90fbf046bdb7e14b..b1be385334bf5ef3f8aa1adfcfdecb10d9adaf3d 100644 (file)
--- a/doc/dev/system-file-format.texi
+++ b/doc/dev/system-file-format.texi
@@ -884,6 +884,9 @@ value @var{code} - @var{bias}, where
 variable @code{bias} from the file header.  For example,
 code 105 with bias 100.0 (the normal value) indicates a numeric variable
 of value 5.
+One file has been seen written by SPSS 14 that contained such a code
+in a @emph{string} field with the value 0 (after the bias is
+subtracted) as a way of encoding null bytes.
 
 @item 252
 End of file.  This code may or may not appear at the end of the data