ODM2 Variable Name Controlled Vocabulary ODM2 Working Group A vocabulary for describing the name of Variables. n-alkane, C18 C18 alkane, normal (i.e. straight-chain) isomer, common name: n-Octadecane, formula : C18H38 Originally from the CUAHSI HIS VariableNameCV. See: http://his.cuahsi.org/mastercvreg/edit_cv11.aspx?tbl=VariableNameCV.