eXtensible Access Control Markup Language
From OASIS. XACML is an XML schema for representing authorization and entitlement policies. However, it is important to note that a compliant Policy Decision Point (PDP) may choose an entirely different representation for its internal evaluation and decision-making processes. That is, it is entirely permissible for XACML to be regarded simply as a policy interchange format, with any given implementation translating the XACML policy to its own local/native/proprietary/alternate policy language sometime prior to evaluation. XACML is expected to address fine grained control of authorized activities, the effect of characteristics of the access requestor, the protocol over which the request is made, authorization based on classes of activities, and content introspection (i.e. authorization based on both the requestor and potentially attribute values within the target where the values of the attributes may not be known to the policy writer). XACML is also expected to suggest a policy authorization model to guide implementers of the authorization mechanism.