TLV 502 indicates the value provided in the PRD policy definitions. This value is used as reference data.
One Policy ID TLV is included in the PER for each policy that is matched for the event. During policy execution, a policy can execute more than one time, so the policy identifier may be included in the policy list multiple times.
In version 1.0, only matched policies are included in the PER, so a PER can be generated without including any Policy Id TLVs.
Policy Group Tracing
Some policies may contain an action that instructs the policy engine to execute a policy group. A policy in a group may also execute another group, increasing the nesting level. A policy can belong to zero or more groups. When tracking which group a policy belongs to, only use the current (i.e., most deeply nested) group. The PER parser must track the current group level. The policy reference data indicates which policies execute groups and which policies exit a group to facilitate tracking the current group and nesting level. When a policy group is exited and there is no matching policy with an action that indicates this, the PER includes a policy ID of zero, to indicate that the group nesting level has been exited.