code: function mapLocalReference (node) {
      if ((node === undefined) || (node === null)) return undefined;
      var ref = _getFirstChildNS(node, 'Ref');
      if ((ref === undefined) || (ref === null)) return undefined;
      return getAttrValue(ref, 'id');
    }
docs: ------------------------------------------------------------------------------ Set of functions for mapping references to artefacts (all map to urns)