Clarified new fsync() docs.
diff --git a/Doc/lib/libos.tex b/Doc/lib/libos.tex
index 8437614..9714036 100644
--- a/Doc/lib/libos.tex
+++ b/Doc/lib/libos.tex
@@ -448,14 +448,15 @@
\end{funcdesc}
\begin{funcdesc}{fsync}{fd}
-Force write of file with filedescriptor \var{fd} to disk.
+Force write of file with filedescriptor \var{fd} to disk. On \UNIX,
+this calls the native \cfunction{fsync()} function; on Windows, the
+MS \cfunction{_commit()} function.
-On Windows this calls the MS \cfunction{_commit()} function. If you're
-starting with a Python file object \var{f}, first do
+If you're starting with a Python file object \var{f}, first do
\code{\var{f}.flush()}, and then do \code{os.fsync(\var{f}.fileno()},
to ensure that all internal buffers associated with \var{f} are written
to disk.
-Availability: \UNIX, and Windows starting in 2.3.
+Availability: \UNIX, and Windows starting in 2.2.3.
\end{funcdesc}
\begin{funcdesc}{ftruncate}{fd, length}