Use Data URIs to Include Media in XML
http://www-128.ibm.com/developerworks/web/library/x-tipdatauri.html

Ogbuji, Uche
IBM
2006

Abstract:

There are many ways to link to non-XML content within XML, including binary content. Sometimes you need to roll all such external content directly into the XML. Data scheme URIs are one way to specify a full resource within a URI, which you can then use in XML constructs. In this tip, Uche Ogbuji shows how to use this to bundle related media into a single file.