Strength of requirements on Accept re: 406

[mnot@…]

The definition of the 406 status code allows servers to override the clients' preferences:

Note: HTTP/1.1 servers are allowed to return responses which are not acceptable according to the accept header fields sent in the request. In some cases, this might even be preferable to sending a 406 response. User agents are encouraged to inspect the header fields of an incoming response to determine if it is acceptable.

However, this isn't really reflected in the Accept-* header requirements; e.g., for Accept:

If an Accept header field is present, and if the server cannot send a response which is acceptable according to the combined Accept field value, then the server SHOULD send a 406 (Not Acceptable) response.

The SHOULD here needs to either be contextualised (perhaps by pasting in a similar note), and/or relaxed to a MAY. Likewise for other Accept-* headers.

[julian.reschke@…]

proposed patch for p2 and p3

[julian.reschke@…]

From [1335]:

Tune strength of requirements on Accept re: 406 (see #285)