[whatwg] Alternate link clarifications [was Re: PaceAutoDiscoveryDraftIsPointless]

James M Snell jasnell at gmail.com
Tue Nov 28 16:26:14 PST 2006

Ian Hickson wrote:
>> [snip]
>>  1. Is the order of alternate link rels in a document significant?
> Good question. The draft hadn't covered that. I've now fixed the spec to 
> say that the order is important in one respect: the first <link>, <a>, or 
> <area> element whose rel="" attribute has the keyword "feed" (which might 
> also be implied by rel=alternate in certain cases) is defined to be the 
> default syndication feed for autodiscovery purposes.

Excellent.  However, wouldn't it be more appropriate to limit this just
to rel="alternate feed"?  I can't imagine that the ordering of "feed"
links that are not also alternates is really all that significant.

>>  2. Are multiple alternate links with the same type attribute
>>     considered to be equivalent regardless of where those links appear
>>     in the document.
> Currently, the location of the link is irrelevant (except for the first 
> one being the default). However, different links with different href="" 
> attributes aren't "equivalent"; they point to different documents. They 
> can also have different titles (title=""), languages (hreflang=""), and 
> preferred media (media="").

Equivalent was the wrong word I think.

Assuming that A includes alternate links to B and C, Can I assume that B
is also an alternate of C; and vice versa?

If that is the case, consider the header of the mozilla.org start page
in which you'll find four distinct alternate links:

 <link rel="alternate" type="application/rss+xml"
       title="Mozilla Announcements"
 <link rel="alternate" type="application/rss+xml"
       title="Mozilla Weblogs"
 <link rel="alternate" type="application/atom+xml"
       title="mozillaZine News"
 <link rel="alternate" type="application/rss+xml"
       title="Mozilla Developer News"

Each represent alternative representations of distinct subsets of the
start page but they are not alternatives to one another.  I'm guessing
that using the "feed" link relation without the "alternate" keyword
would have been more appropriate

> I hope this helps. If you have any other feedback, or if you'd like the 
> spec changed in any way, please let us know. I am very interested in 
> addressing any requirements the Atom community may have.

Yes, it does help.  Thanks for taking the time.

- James

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