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

    This routine changes the object name in the read-write lock
    object specified by rwlock to the value specified by name. To
    set a new read-write lock object's object name, call this routine
    immediately after initializing the read-write lock object.

    The object name is a C language string and provides an identifier
    that is meaningful to a person debugging a multithreaded
    application. The maximum number of characters in the object name
    is 31.