UML 2.0 models are serialized in XMI according to the rules specified by the MOF 2.0: XMI Mapping Specification. The XML schema for MOF 2.0 models that support the MOF 2.0: XMI Mapping specification is available in OMG document ad/2002-12-09.
The XMI for serializing the UML 2.0: Infrastructure as an instance of MOF 2.0 according to the rules specified by the MOF 2.0: XMI Mapping Specification is available in OMG document ad/2003-04-04. It is expected that the normative XMI for this specification will be generated by a Finalization Task Force, which will architecturally align and finalize the relevant specifications.