public static IdentifierUse fromCode(String codeString) throws Exception {
            if (codeString == null || "".equals(codeString))
                return null;
        if ("usual".equals(codeString))
          return usual;
        if ("official".equals(codeString))
          return official;
        if ("temp".equals(codeString))
          return temp;
        throw new Exception("Unknown IdentifierUse code '"+codeString+"'");
        }