0 4 0 http://purl.obolibrary.org/obo/RBO_00010059 ionization cluster size 'ionization cluster size' SubClassOf 'physical object quality' http://purl.obolibrary.org/obo/RBO_00010060 ionization cluster size measurement datum 'ionization cluster size measurement datum' SubClassOf 'scalar measurement datum' http://purl.obolibrary.org/obo/RBO_00010061 particle track penumbra 'particle track penumbra' SubClassOf 'spatial region' http://purl.obolibrary.org/obo/RBO_00010062 particle track core 'particle track core' SubClassOf 'spatial region'