Re: ISSUE-28 (http-mime-override): Content type rules in HTML 5 overlaps with the HTTP specification? [HTML Principles/Requirements]

On Jan 25, 2008, at 5:30 PM, Boris Zbarsky wrote:

>
> One more thought I had about this today.  Is real reason the  
> sniffing in the spec is a MUST because UAs must not do any sniffing  
> other than what's specified?   If so, it might make more sense to  
> say that as a MUST and say the existing sniffing stuff as a MAY.

Another reason is that inconsistent sniffing between browsers is  
potentially a security issue, though I'm not sure this applies to text  
vs. binary sniffing.

In other cases (like <img> entirely ignoring the server-reported  
Content-Type for binary image formats), I think the requirement should  
remain a MUST for interoperability. Binary image formats already have  
unique in-stream identifiers and it doesn't ever make sense to treat a  
GIF as a JPEG so this doesn't have the same issues as sniffing for  
binaries or RSS feeds where there could indeed be ambiguity.

Regards,
Maciej