Visio 2003 UML to export to XMI standard documents

Download this Visio 2003 add-in here. From, XMI:

XMI is a model driven XML Integration framework for defining, interchanging, manipulating and integrating XML data and objects. XMI-based standards are in use for integrating tools, repositories, applications and data warehouses. Provides  rules by which a schema can be generated for any valid XMI-transmissible MOF-based metamodel.