6. Reprioritization

After a client sends a request, it may be beneficial to change the priority of the response. For example, a web browser might issue a speculative request for a CSS file, but then discover after loading the HTML document that the file is not needed. In such a case, the client can change the priority of that file to the lowest priority or cancel the request.

The HTTP version-specific PRIORITY_UPDATE frame types defined in Section 7 are used for such reprioritization.

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