On 19 Jan 2006, at 11:53 am, David Powell wrote:

Possibly, but that solution isn't perfect. There is a tradeoff between
supplying an inaccurate type, and supplying no type at all. This TAG
finding [1] discusses the issue quite thoroughly.

[1] http://www.w3.org/2001/tag/doc/mime-respect-20040225

The risk in providing an inaccurate mime-type in the content or link
elements, is that a user-agent such as a mobile device, might not
attempt to fetch the content at all if they don't support the advisory
MIME type, even though if they had requested the type, and conneg had
taken place, they could have been served a different type that they
could have handled.

If you read the W3C finding carefully, it doesn't actually cover this exact problem. It comes close in scenario 2 in section 2, section 4.1 and section 5, but doesn't quite get there - all only cover when the advisory type is wrong outright, rather than misleading because of conneg.

The recommendation at the end of section 4.1 seems appropriate though. If the advisory type attribute is incompatible, the client should query the resource to double check, or at least offer the user the option of double checking and/or loading the resource anyway.

Graham

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