[uf-discuss] VIA or VIA SELF to indicate authoritative hCard [was: UID URL to indicate (relatively) more authoritativehCard (Was: Vote on this: rel="me self" to indicate anauthoritative hCard)]

Ryan Cannon ryan at ryancannon.com
Thu Feb 8 18:22:06 PST 2007

On Feb 8, 2007, at 8:03 PM, Joe Andrieu wrote:
> Why not just have a "via" point to "source" hCards and any hCard  
> that is
> self-referential is  "authoritative"?  That seems both easy for
> publishers and relatively straightforward for parsers.  Keep
> dereferencing @rel="via" attributes until you find one that  
> dereferences
> to itself with @rel="via self".  Once you get to one that says "I'm my
> own source," you've got a reasonable assertion of authority.
> Ryan Cannon suggested this previously [2], but it seemed to get  
> lost in
> "uid url" conversations.
> [2] http://microformats.org/discuss/mail/microformats-discuss/2007- 
> January/008443.html

Thanks--it didn't get much traction earlier, and I have yet to see a  
that makes more sense based on the terms as they are currently defined.

> Here's the formal def for @rel="self"
>    3.  The value "self" signifies that the IRI in the value of the  
> href
>        attribute identifies a resource equivalent to the containing
>        element.
> So, refering hCards use @rel="via" and the authoritative hCard uses
> @rel="via self".  And if you don't want to use an <a> link that is
> self-referential use a span with class="via self url".
> And if the url in the rel is also the aid, the @rel="via uid" and
> @rel="via self uid" should work fine.

One catch: if the value in the URI with @rel=self has to be equivalent,
then wouldn't the data embedded in the two hCards have to be exactly the

Also, how would @rel="uid" be defined as an HTML linktype, in a manner
different than the ATOM definition for @rel="via" (see my previous post)

I suggest that to determine a uid field and authority, hCard parsers
look for @class="uid" (parsed as a string, per the current spec not
as a URL), that failing, the parsers may optionally follow any links
with @rel="via" and attempt to extract a uid from the referenced hCard.


   * @rel="via" links can form a chain of authority.
   * @rel="via" links  do not require the author of the linked hCard to
     maintain them.
   * @rel="via" links need not be included in the actual hCard if the
     author does not want them to be.
   * All class names and link types maintain their current
     definitions, which has the least chance of breaking current
     implementations (as opposed to <a href="url uid">, which requires
     parsing rule changes and @rel="self" or @rel="me", which have
     different semantics.

Are there problems with this suggestion that I'm not seeing?

Ryan Cannon

Interactive Developer
MSI Student, School of Information
University of Michigan

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