The main purpose of ISO/IEC 19503:2005 (XMI) is to enable easy interchange of metadata between application development lifecycle tools (such as modeling tools based on the Unified Modeling Language (UML), ISO/IEC 19501, and metadata repositories/frameworks based on the Meta Object Facility (MOF), ISO/IEC 19502) in distributed heterogeneous environments. ISO/IEC 19503:2005 integrates three key industry standards:

• XML, eXtensible Markup Language, a W3C standard;
• UML, Unified Modeling Language, an OMG modeling specification which is now ISO/IEC 19501;
• MOF, Meta Object Facility (ISO/IEC 19502).

ISO/IEC 19503:2005 provides specifications for

• a set of XML Schema Definitions (XSD) production rules for transforming MOF-based metamodels into XML Schemas;
• a set of XML Document production rules for encoding and decoding MOF-based metadata;
• design principles for XMI-based Schemas and XML documents;
• a set of production rules for importing XML DTDs to a MOF-based metamodel.

ISO/IEC 19503:2005 enhances metadata management and metadata interoperability in distributed object environments in general and in distributed development environments in particular. While it addresses stream-based metadata interoperability in the object analysis and design domain, ISO/IEC 19503:2005 (in part because it is MOF based) is equally applicable to metadata in many other domains.