REFERENCE(L_NODE_IN) TYPE WRF_MATGRP_STRUC-PARENT
VALUE(HIERARCHY_PARENT) TYPE WRF_MATGRP_STRUC-PARENT
VALUE(HIERARCHY_PARENT) TYPE WRF_MATGRP_STRUC-PARENT OPTIONAL
REFERENCE(PARENT) LIKE WRF_MATGRP_STRUC-PARENT OPTIONAL