The following DataNodes have no identifier: 2
http://classic.wikipathways.org/instance/WP3145_r80707 http://rdf.wikipathways.org/Pathway/WP3145_r80707/DataNode/ca217 (DNA, proteins, metabolites)
http://classic.wikipathways.org/instance/WP3145_r80707 http://rdf.wikipathways.org/Pathway/WP3145_r80707/DataNode/a15ad (Methylated products)
More details at https://www.wikipathways.org/WikiPathwaysCurator/DataNodesTests/dataNodesWithoutIdentifier