26 Containers library [containers]

26.2 Container requirements [container.requirements]

26.2.5 Insert return type [container.insert.return]

The associative containers with unique keys and the unordered containers with unique keys have a member function insert that returns a nested type insert_­return_­type.
That return type is a specialization of the type specified in this subclause.
template <class Iterator, class NodeType>
  Iterator position;
  bool     inserted;
  NodeType node;
The name INSERT_­RETURN_­TYPE is exposition only.
INSERT_­RETURN_­TYPE has the template parameters, data members, and special members specified above.
It has no base classes or members other than those specified.