Extensible Markup Language (XML) was developed by the World Wide Web Consortium as a version of Standard Generalized Markup Language (SGML) for electronic publishing and data interchange. (see ) Designed for Web content providers, XML is quickly becoming a common metadata representation in Web objects and elsewhere. As a standard for metadata representation, XML is complementary to GILS in the same way as SGML. In the World Wide Web Consortium work on XML Schema and Resource Description Framework, a further possibility is emerging in using XML as a way to specify multiple metadata schemes and place the various sets of semantics into a commonly accessible and automated registry. Standards work in this direction is clearly part of the evolution of GILS.