XML Base: XML, W3C Recommendation, Uniform Resource Identifier, World Wide Web Consortium

XML Namespace: Namespace (Computer Science), XML, Internationalized Resource Identifier, Uniform Identifier

XML Encryption: XML, World Wide Web Consortium, Signature, International, Standards Organization

XML Information Set: W3C Recommendation, XML, Namespace, Well Formed Document

XBEL: XML, Uniform Resource Identifier, Galeon, Konqueror, Arora (Browser)