Water quality Variables associated with water quality variables or processes Originally from CUAHSI HIS GeneralCategoryCV. See http://his.cuahsi.org/mastercvreg/edit_cv11.aspx?tbl=GeneralCategoryCV. ODM2 Variable Type Controlled Vocabulary ODM2 Working Group A vocabulary for describing the type of Variables. VariableTypes provide a way to group Variables into categories for easier querying and filtering.