/sys$common/syshlp/helplib.hlb RMS, RMS Control Block Macros, $XABSUM  *Conan The Librarian (sorry for the slow response - running on an old VAX)

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

    Format

      $XABSUM  NXT=next-xab-address