3. Conformance Criteria

This specification is written for hosts and user agents.

A conformant host is a host that implements all of the requirements listed in this specification that are applicable to hosts.

A conformant user agent is a user agent that implements all of the requirements listed in this specification that are applicable to user agents.

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119].