A host of standards
There are a number of related standards and works in progress that supplement the XML language itself. Extensible Style sheet Language (XSL) and the associated XSL Tranformations (XSLT, www.w3.org/TR/xslt) define stylesheets for use with XML. XML Linking Language (XLink,
XML Query addresses another aspect of extracting a subset of data contained in an XML document by providing a query language similar to those used with databases. If you imagine an XML document containing a list of personal information, an appropriate XML Query would let you extract a list of names and phone numbers of those people living in Western Australia.
XML also serves as the basis for other languages, such as Mathematical Markup Language (MathML, www.w3.org/TR/REC-MathML/), Extensible Hypertext Markup Language (XHTML, www.w3.org/TR/xhtml1/) and Synchronised Multimedia Integration Language (SMIL, www.w3.org/TR/smil20/).
