An umbrella project for various stdlib-like containers with specific properties. Currently contains only six closely related containers: closed_hash_set, closed_hash_map, linked_hash_set, linked_hash_map, forward_hash_set and forward_hash_map. The first two are very similar to TR1 unordered_set and unordered_map. The linked ones provide additional functionality, while forward hash tables are more efficient than linked, but have restricted interface. In some cases performance of the closed_hash_* containers can be improved even further with optional intrusiveness support.