Extensible Access Control Markup Language
Became an OASIS standard in February 2003. XACML defines a general policy language used to protect resources as well as an access decision language.
See Phil Griffin's [http://dev2dev.bea.com/pub/a/2004/02/xacml.html Introduction To XACML] for some background. See also [http://sunxacml.sourceforge.net/ Sun's XACML Implementation] and the [http://www.oasis-open.org/committees/tc_home.php?wg_abbrev=xacml OASIS technical committee] for XACML.