user, and spell out a x-platform use limitation.
\optional{, dir}}
This function operates exactly as \function{TemporaryFile} does,
except that the file is guaranteed to have a visible name in the file
-system. That name can be retrieved from the \member{name} member of
-the file object.
+system (on \UNIX, the directory entry is not unlinked). That name can
+be retrieved from the \member{name} member of the file object. Whether
+the name can be used to open the file a second time, while the
+named temporary file is still open, varies across platforms (it can
+be so used on \UNIX; it cannot on Windows NT or later).
\versionadded{2.3}
\end{funcdesc}