UML22 — UML 2 XMI DTD requirement

In section 6.5.1 of both the RFP for the UML 2 Superstructure and the RFP for the UML 2 Infrastructure it is required that

Proposals shall specify an XMI DTD for the UML metamodel.

This was based on the assumption that such schemas carry sufficient information for tool vendors to construct facilities for meaningful interchange of models. Unfortunately, due to the introduction of certain more complex features such as package merge in UML 2.0, these schemas are not sufficient. On the other hand, the XMI for the individual compliance levels (Lm, L0, L1, L2, and L3) is sufficient for the interchange objective. Therefore, instead of the XMI schemas, it is proposed to make the latter normative for the UML 2 Superstructure and Infrastructure specs.

This is resolved by the resolution to 3898 and the explanatory text for 8678.