One way to explain the architecture proposed by this document is to examine the roles which are defined for various entities in the architecture and to describe what is required of each entity in order for the proposed system to work properly. The following sections identify four types of entities within this architecture: users and user agents, the Internet Policy Registration Authority, Policy Certification Authorities, and other Certification Authorities. For each type of entity, this document specifies the procedures which the entity must execute as part of the architecture and the responsibilities the entity assumes as a function of its role in the architecture.