atom:content's src and server-driven content negotiation

[Andreas Sewe]

I don't want to start yet another discussion about violating SHOULD 
level requirements but I can't think of any better way to handle the 
following situation (but hopefully you can :-):

Suppose the host www.example.com uses HTTP/1.1's server-driven content 
negotiation for its resource /img which has both image/png and 
image/svg+xml representations. Furthermore these representations can be 
accessed explicitly as /img.png and /img.svg, respectively.

Now a straight-forward way to compose an entry describing /img would be 
as follows:

<entry>
  <title>Some Example Image</title>
  <summary>A short summary of the example image</summary>
  <link rel="alternate" type="image/png"
        href="http://www.example.com/img.png"; />
  <link rel="alternate" type="image/svg+xml"
        href="http://www.example.com/img.svg"; />
  <content src="http://www.example.com/img"; />
  <!-- author, id, updated -->
</entry>

Note, however, that a type attribute on the content element cannot be 
used since /img is a negotiated resource -- this violates the SHOULD in 
4.1.3.2.: 'If the "src" attribute is present, the "type" attribute 
SHOULD be provided [...].'

Of course one can compose an entry without a content element, simply 
listing /img among the alternate versions, but at least to me this 
feels, in the above scenario, wrong (although I cannot really put my 
finger on it):

<entry>
  <title>Some Example Image</title>
  <summary>A short summary of the example image</summary>
  <link rel="alternate"
        href="http://www.example.com/img"; />
  <link rel="alternate" type="image/png"
        href="http://www.example.com/img.png"; />
  <link rel="alternate" type="image/svg+xml"
        href="http://www.example.com/img.svg"; />
  <!-- author, id, updated -->
</entry>

So do you have any suggestions how to best deal with a scenario like 
this? Which of the above entries is preferable?

Regards,

Andreas Sewe