Head and Neck Cancer Ontology	Radiation Oncology Structures Ontology	Source
urn:absolute:RadiationOncologyStructuresOntology#Skin	http://ontology.lst.tfo.upm.es/BD2D/ctn#Tissue_Invasion_ExtraNodalExtension_to@@1	LOOM
urn:absolute:RadiationOncologyStructuresOntology#Larynx	http://ontology.lst.tfo.upm.es/BD2D/ctn#Tumor_Region@@4	LOOM