Policy set for evaluating the subject:role attributes.
This implements an RBAC policy. This policy set matches
subject roles and refers to permission policy sets.
urn:va:xacml:2.0:interop:rsa8:role:hl7:physician
urn:va:xacml:2.0:interop:rsa8:policysetid:N:RPS:med-rec-vrole