Firstly, I think the bimap library is great. What would suit my situation is to use a container type of relation that allowed storage of some information with each relationship. Effectively: map_of_relation< UserDefineValueType, KeyComp > (and related multimap, unordered_map, etc). As a usage example, in database terms, TableA references TableB. Attached to the TableA->TableB relationship, would be a bimap of rows in TableA that reference rows in TableB. So... typedef bimap< set_ofRows:iterator, set_ofRows:iterator, map_of< RelationshipDescription >

RowRelationships;

typedef bimap< multiset_ofTable::Ptr, multiset_ofTable::Ptr, map_of_relation< shared_ptr<RowRelationships> >

TableRelationships;

Is this easy to add with the current bimap architecture? Neil