2. Conventions and Definitions

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here.

In this document, we use the term "IP proxy" to refer to the HTTP server that responds to the IP proxying request. The term "client" is used in the HTTP sense; the client constructs the IP proxying request. If there are HTTP intermediaries (as defined in Section 3.7 of HTTP) between the client and the IP proxy, those are referred to as "intermediaries" in this document. The term "IP proxying endpoints" refers to both the client and the IP proxy.

This document uses terminology from [QUIC]. Where this document defines protocol types, the definition format uses the notation from Section 1.3 of QUIC. This specification uses the variable-length integer encoding from Section 16 of QUIC. Variable-length integer values do not need to be encoded in the minimum number of bytes necessary.

Note that, when the HTTP version in use does not support multiplexing streams (such as HTTP/1.1), any reference to "stream" in this document represents the entire connection.