def _expt__CMORvar(self):
    """Return set of CMORvar item identifiers for CMORvars requested for this experiment"""
    cmv = set()
    for u in self._get__requestItem():
      ri = self._inx.uid[u]
      rl = self._inx.uid[ri.rlid]
      for i in rl._get__CMORvar():
        cmv.add(i)
    return cmv