- AgreementID 
- A small unit of information that indicates both parties have agreed on a common
     proposal. An agreementID is the fingerprint of an accepted proposal. The presence of the
     agreementID in the P3P headers is the definitive declaration of which agreements for a
     given realm are in effect for a given transaction. 
- Assuring Party 
- Within P3P, an assuring party is an entity which makes some statement of assurance about
     a proposal (e.g. that practices are audited, or are in compliance with certain data
     collection guidelines). 
- PUID 
- PUID := hash(GUID, Realm, AgreementID). The PUID is an optional way for the user to
     identify herself to a service under a particular agreement. PUIDs correspond directly to a
     specific realm and agreement. PUIDs are like cookies, but are under P3P control and are
     simple numberical values.