AtomPub binding:

Section 3.6 AtomPub Service Document, states...

"Types Collection: Collection containing all the types in the repository".

However, section 3.7 Service Collections, describes the 'Types Children Collection' (in 3.7.5), as

"This is a collection described in the service document that contains the types in the repository under the specified parent type. If no parent type is specified, then the base types are returned in the feed."

The problem is the Types Children Collection does not support the containing of all types in the repository. This follows the domain model (and web services).