NENA Route Policy

This section summarizes the syntax and semantic of the policy language used for making call routing decisions. Policy is represented in anRFC 4745 [146]-compliant common policy schema.A policy document is an XML document formatted according to the schema defined in RFC 4745. This document inherits the MIME type of commonpolicy documents namely application/auth-policy+xml. As described in RFC 4745 this document is composed of rules that contain three parts -conditions actions and transformations. The conditions statement may either evaluate to 'true' or 'false'. If it evaluates to 'true' thenthe action and the transformations part of the rule is executed. In order to deal with the case where multiple conditions parts evaluate to'true' a conflict resolution mechanism is described to avoid conflicting actions to be executed. Common Policy (RFC 4745) describes aconflict resolution framework and this document extends it with a priority-based mechanism whereby each rule has an associated priority value that indicates the relative importance of the specific rule with the semantic that a higher value gets precedence over a rule with a lowervalue. The transformations part of a rule is not used by this application.