NAME
        LockRealTime -- prevent other tasks from changing internal structures.
                        (V37)

   SYNOPSIS
        lockHandle = LockRealTime(lockType);
        D0                        D0

        aptr lockrealtime(ulong);

   FUNCTION
        This routine will lock the internal sempahores in the RealTime library.
        If they are already locked by another task, this routine will wait
        until they are free.

   INPUTS
        lockType - the internal list to lock. Only RT_CONDUCTORS is
                   currently defined.

   RESULT
        handle - if lockType is valid, returns a value that must be passed
                 later to unlockrealtime() to unlock the list. returns null
                 if passed an invalid lock type.

   SEE ALSO
        unlockrealtime()