Two new types are introduced, in addition to the types defined in the Associative Container and Reversible Container requirements.
||The type of a Strict Weak Ordering used to compare keys. Its argument type must be X::key_type.|
||The type of a Strict Weak Ordering used to compare values. Its argument type must be X::value_type, and it compares two objects of value_type by passing the keys associated with those objects to a function object of type key_compare.|