Added os.altsep; this is '/' on DOS/Windows, and None on systems with
a sane filename syntax.
diff --git a/Doc/lib/libos.tex b/Doc/lib/libos.tex
index f17ce95..1853b3f 100644
--- a/Doc/lib/libos.tex
+++ b/Doc/lib/libos.tex
@@ -52,13 +52,19 @@
\end{datadesc}
\begin{datadesc}{sep}
-The character used by the OS to separate pathname components, e.g.\
-\code{'/'} for POSIX or \code{':'} for the Mac. Note that knowing this
+The character used by the OS to separate pathname components,
+e.g. \code{'/'} for POSIX or \code{':'} for the Mac. Note that knowing this
is not sufficient to be able to parse or concatenate pathnames---better
use \code{os.path.split()} and \code{os.path.join()}---but it is
occasionally useful.
\end{datadesc}
+\begin{datadesc}{altsep}
+An alternative character used by the OS to separate pathname components,
+or \code{None} if only one separator character exists. This is set to
+\code{'/'} on DOS/Windows systems where \code{sep} is a backslash.
+\end{datadesc}
+
\begin{datadesc}{pathsep}
The character conventionally used by the OS to separate search patch
components (as in \code{\$PATH}), e.g.\ \code{':'} for POSIX or