The following DataNodes have no identifier: 4
http://classic.wikipathways.org/instance/WP1060_r117558 http://rdf.wikipathways.org/Pathway/WP1060_r117558/DataNode/d23 (MMP12)
http://classic.wikipathways.org/instance/WP1060_r117558 http://rdf.wikipathways.org/Pathway/WP1060_r117558/DataNode/d77 (MMP21)
http://classic.wikipathways.org/instance/WP1060_r117558 http://rdf.wikipathways.org/Pathway/WP1060_r117558/DataNode/efd (MMP23A)
http://classic.wikipathways.org/instance/WP1060_r117558 http://rdf.wikipathways.org/Pathway/WP1060_r117558/DataNode/fc8 (MMP26)
More details at https://www.wikipathways.org/WikiPathwaysCurator/DataNodesTests/dataNodesWithoutIdentifier