returned by \function{ctime()}. The same platform caveats apply; see
the local \UNIX{} documentation for restrictions or additional
supported directives. If \var{string} cannot be parsed according to
-\var{format}, \exception{ValueError} is raised.
+\var{format}, \exception{ValueError} is raised. Values which are not
+provided as part of the input string are filled in with default
+values; the specific values are platform-dependent as the XPG standard
+does not provide sufficient information to constrain the result.
+
+\strong{Note:} This function relies entirely on the underlying
+platform's C library for the date parsing, and some of these libraries
+are buggy. There's nothing to be done about this short of a new,
+portable implementation of \cfunction{strptime()}.
Availability: Most modern \UNIX{} systems.
\end{funcdesc}