Re: Request to register "identifier" relation type

Peter Williams <> Wed, 09 August 2017 17:40 UTC

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From: Peter Williams <>
Date: Wed, 9 Aug 2017 11:40:40 -0600
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Subject: Re: Request to register "identifier" relation type
To: Herbert Van de Sompel <>
Cc: Ed Summers <>, link-relations <>, Geoffrey Bilder <>, Michael Nelson <>, Simeon Warner <>, "John A. Kunze" <>
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> The semantics are the same in all scenarios: the target URI is preferred
> for referencing.

Given how much "reference" has come up in this discussion perhaps that
would be a better name for this relation? Or something based on it?

On Wed, Aug 9, 2017 at 11:20 AM, Herbert Van de Sompel <>

> On Aug 9, 2017, at 18:59, Peter Williams <> wrote:
> This discussion has convinced me that no existing relation is a good match
> for the proposed semantics. However, i am concerned that the proposed
> relation has taken this much discussion to understand. The confusion it
> generated here does not bode well for it being used properly by mere
> mortals.
> Personally, I think the confusion was largely caused by thinking from the
> perspective that this was canonical or bookmark, and us having to show it
> was not.
> I hope that a reading of the I-D itself, without coming from the
> canonical/bookmark perspective does make it clear what "identifier" is
> about. Various scenarios illustrate what it is intended for, and, IMO, the
> short description "preferred for referencing" is clear too.
> I think a more concrete name would greatly improve the usability. Finding
> a more concrete name will be challenging because this relation conflate
> several different relationships into a single name. These different
> semantics are called out in the I-D in sections 3.1-3.4.
> The semantics are the same in all scenarios: the target URI is preferred
> for referencing.
> Having multiple relations, one for each semantic, might be another way to
> address the usability issues. Some of those use cases seem to be covered by
> existing relations. For example, `canonical` seems tailor made for the
> "Version Identifiers" use case.
> Our blog post shows that "canonical" is not appropriate at all for the
> Wikipedia versioning case. They want the generic URI (current version) to
> be indexed - canonical. They want the version-specific URI to be referenced
> - identifier.
> Greetings
> Herbert
> For other use cases, such as "Multi-Resource Publications" and "Persistent
> Identifiers", there don't seem to be any existing relations that would
> work. Relations for those narrower use cases would be much easier to
> understand and use.
> Peter
> On Wed, Aug 9, 2017 at 10:17 AM, Ed Summers <> wrote:
>> Hi Herbert,
>> > On Aug 9, 2017, at 10:35 AM, Herbert Van de Sompel <>
>> wrote:
>> >
>> > * On August 5, Ed Summers posted a question regarding applying
>> "bookmark" to <link> to the WHATWG list, see
>> 017Aug/0001.html. There are no responses to this post, so far.
>> There have been a few responses if you look at the list of emails for
>> August:
>> > * On August 9, Ed Summer posted a similar question to WHATWG/HTML
>> GitHub, see There is a
>> reaction from @annevk who (1) speculates that the reason "bookmark" is not
>> to be used with <link> might be in order not to overlap with "canonical"
>> (2) suggests the use of "canonical" :-)
>> Yes, canonical seems to be the relation that most people are reaching for
>> initially. I did myself on reading your I-D. The fact that seasoned hands
>> like Kevin Marks and Anne van Kesteren are as well says something.
>> > * Michael Nelson has further explored "bookmark" and has confirmed that
>> there effectively is a reason for not allowing "bookmark" in <link>. It is
>> related to its target use case: surfacing a link for content contained in a
>> *part* of a page. Hence, Michael concludes that making "bookmark" usable
>> with <link> will most likely not happen. @annevk's GitHub response does not
>> seem to contradict that. Michael based his findings on studying
>> and
>> He
>> may write another blog post about this, but, for now, here's how he
>> explained on Twitter
>> Yes, it looks like that's probably where things will sit. As Anne
>> indicated it's likely that rel=bookmark cannot be used with <link> because
>> of perceived confusion it would cause with canonical. The semantics of
>> parts of pages vs the page itself don't seem terribly significant to me
>> from an implementation perspective. Unfortunately 'identifier' will also
>> probably cause some confusion as well. As systems that rely on 'identifier'
>> get developed that will be something for them to deal with.
>> Thanks for considering all the questions and tracking the conversation
>> over on the WHATWG list. It speaks to the spirit of what you all are trying
>> to achieve with this I-D.
>> //Ed