Policy Decision Point (PDP)
The PDP, Policy Decision Point, is in charge of evaluating the defined rules. The Policy Decision Point is essentially a policy compiler. The PDP must verify that the specified rules are within the scope of the rule authors authority. The PDP provides the authorization to the PEP.
XACML Policy Management
The policy language is used to describe general access control requirements, and has standard extension points for defining new functions, data types, combining logic, etc. The request/response language lets you form a query to ask whether or not a given action should be allowed, and interpret the result.
It is possible to import an existing PolicySet into the system. The file to import must be a well-formed XML.
To know more about XACML, read XACML 2.0 Standard Specification