delta O18 Expressed as oxygen-18 Adapted from the CUAHSI HIS SpeciationCV. See: http://his.cuahsi.org/mastercvreg/edit_cv11.aspx?tbl=SpeciationCV. ODM2 Speciation Controlled Vocabulary ODM2 Working Group A vocabulary for describing the type of SpatialOffset that exists between two SamplingFeatures.