Although UAF is a UML profile, the US DoD, working with the OMG, incorporated language into the spec that says a non-UML modeling tool can support UAF by supporting the domain metamodel. System Architect supports the UAF domain metamodel with UML concepts of data centricity, inheritance of the metamodel, and UML diagram notations. However, its support is built directly against the domain metamodel, so there are no ‘levels of indirection’ – for example a UML implementation puts an OperationalExchange on a Message flow between Object lifelines on Operational Interaction (Sequence) diagram; in System Architect, the OperationalExchange IS the message line between Roles represented by vertical lifelines on an Operational Interaction (Sequence) diagram.