Handling of HTTP response codes for <embed>, was: [whatwg] <embed> feedback

Ian Hickson wrote:
> ...
> On Sun, 7 May 2006, Simon Pieters wrote:
>>> I think for <img> you want to only support image/* types (e.g. not 
>>> text/plain or text/html, not sure about image/svg+xml either, since 
>>> there is no difference between that and application/xhtml+xml); and 
>>> you want to only show them for 200 (or 301-200).
>>> [...]
>>> For <embed> you want to show only things that require plugins, and 
>>> only if they have 200 (or 301-200) responses.
>> The only browser to my knowledge that only support 200 (or 301-200) 
>> responses for <img> and <embed> is IE5/Mac. Safari, Opera, Mozilla and 
>> IE all load the resourse for <img> and <embed> regardless of the 
>> response. (In the real world it works fine because error responses are 
>> normally text/html.)
> 
> This is now what <img> and <embed> say.
> ...

That doesn't sound good. Is there any research on for how much of the 
consisting content this is needed?

BR, Julian