Cisco Systems Nortel Networks Extreme Networks Cisco Systems This document defines a set of policy rule classes for describing quality of service (QoS) policies. This document structures QoS policy information as instances of policy rule classes. A policy rule class (PRC) is an ordered set of scalar attributes. Policy rule classes are arranged in a hierarchical structure similar to tables in SNMP's SMIv2 [SNMP-SMI]. As with SNMP tables, they are identified by a sequence of integer identifiers (an Object Identifier).