The XML Metadata Interchange (XMI) is an Object Management Group (OMG) standard for exchanging metadata information via Extensible Markup Language (XML).
It can be used for any metadata whose metamodel can be expressed in Meta-Object Facility (MOF), a platform-independent model (PIM).
This means exchanging files between UML modeling tools using XMI is rarely possible.
Examples of XMI, and lists of the XML tags that make up XMI-formatted files, are available in the version 2.5.1 specification document.
The Diagram Definition OMG project is another alternative for metadata interchange, which can also express the layout and graphical representation.