ODM2 Variable Name Controlled Vocabulary ODM2 Working Group A vocabulary for describing the name of Variables. Cobalt-60 A synthetic radioactive isotope of cobalt with a half-life of 5.27 years. Originally from the CUAHSI HIS VariableNameCV. See: http://his.cuahsi.org/mastercvreg/edit_cv11.aspx?tbl=VariableNameCV.