The mechanisms described here MAY be used for HTTP transactions over any underlying protocol. This includes plain-text HTTP over TCP/IP connections as well as encrypted HTTP over SSL connections, as well as HTTP over any other communications protocol network designers wish to implement.
URLs MAY contain TCP/IP port numbers, as specified in RFC 2396 [URI]. For the purposes of P3P, the different ports on a single host MUST be considered to be seperate "sites". Thus, for example, the policy reference file at the well-known location for www.example.com on port 80 (http://www.example.com/w3c/p3p.xml) would not give any information about the policies which apply to www.example.com when accessed over SSL (as the SSL communication would take place on a different port, 443 by default).
This document does not specify how P3P policies may be associated with documents retrieved by means other than HTTP. However, it does not preclude future development of mechanisms for associating P3P policies with documents retrieved over other protocols. Furthermore, additional methods of associating P3P policies with documents retrieved using HTTP may be developed in the future.