Listing 6

typedef multi_index_container<
  employee,
  indexed_by<
    ordered_unique<identity<employee> >,
    ordered_non_unique<member<employee, std::string, &employee::name> >,
    ordered_non_unique<
      member<employee, int, &employee::age>,
      std::greater<int> // default is std::less<int>
    >
  >
> company;