Not All SMILs

The Synchronized Multimedia Integration Language (SMIL), the latest W3C recommendation, is completely in line with the trend of the consortium for the last few months, in that it builds on the other work of the body in an incremental fashion. In this case it means that SMIL, which is used to create time-based presentations that integrate different media objects into a single document, is based on XML.

http://www.webdeveloper.com/xml/xml_062698.html