VMS Help RMS, RMS Control Block Macros, $XABFHC  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    The $XABFHC macro allocates and initializes a XABFHC. No value is
    returned for this assembly-time operation.

    Format

      $XABFHC  NXT=next-xab-address