Wikipedia
UXF
In computing, UXF is an initialism for UML eXchange Format, see Unified Modeling Language.
UXF is a XML-based model interchange format for UML, which is a standard software modeling language. UXF is a structured format described in 1998 and intended to encode, publish, access and exchange UML models.
More recent alternatives include XML Metadata Interchange and OMG's Diagram Definition standard.