NAME
        ParentOfFH -- returns a lock on the parent directory of a file (V36)

   SYNOPSIS
        lock = ParentOfFH(fh)
        D0               D1

        bptr parentoffh(bptr)

   FUNCTION
        Returns a shared lock on the parent directory of the filehandle.

   INPUTS
        fh   - Filehandle you want the parent of.

   RESULT
        lock - lock on parent directory of the filehandle or null for failure.

   SEE ALSO
        Parent(), lock(), unlock() duplockfromfh()