Guido pointed out that all names in the sys module have no underscore,
diff --git a/Doc/lib/libsys.tex b/Doc/lib/libsys.tex
index 5cc833d..bbea623 100644
--- a/Doc/lib/libsys.tex
+++ b/Doc/lib/libsys.tex
@@ -20,7 +20,7 @@
\code{argv} has zero length.
\end{datadesc}
-\begin{datadesc}{byte_order}
+\begin{datadesc}{byteorder}
An indicator of the native byte order. This will have the value
\code{'big'} on big-endian (most-signigicant byte first) platforms,
and \code{'little'} on little-endian (least-significant byte first)