 results are undefined if
this function is called with an uninitialized read-write lock. 
</P>
<P><B>pthreads-win32</B> defines <B>_POSIX_READER_WRITER_LOCKS</B> in
pthread.h as  200112L to indicate that the reader/writer routines are
implemented and may be used.</P>
<H2><A HREF="#toc3" NAME="sect3">Return Value</A></H2>
<P>The <B>pthread_rwlock_timedrdlock</B> function shall return zero
if the lock for reading on the read-write lock object referenced by
<I>rwlock</I> is acquired. Otherwise, an error number