The following DataNodes have no identifier: 1
http://classic.wikipathways.org/instance/WP4501_r107729 http://rdf.wikipathways.org/Pathway/WP4501_r107729/DataNode/d6946 (isovanilloylglycine)
More details at https://www.wikipathways.org/WikiPathwaysCurator/DataNodesTests/dataNodesWithoutIdentifier