Extensible Prioritization Scheme for HTTP

This document describes a scheme for prioritizing HTTP responses. This scheme expresses the priority of each HTTP response using absolute values, rather than as a relative relationship between a group of HTTP responses. This document defines the Priority header field for communicating the initial priority in an HTTP version-independent manner, as well as HTTP/2 and HTTP/3 frames for reprioritizing the responses. These share a common format structure that is designed to provide future extensibility.