VMS Help POSIX Threads, PTHREAD routines, pthread_rwlockattr_destroy, Description  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    This routine destroys the read-write lock attributes object
    referenced by attr; that is, the object becomes uninitialized.

    After successful completion of this routine, the results of using
    attr in a call to any routine (other than pthread_rwlockattr_
    init()) are unpredictable.