Subject: Re: Review and URN assignment for draft-seantek-xmlns-urn-00

From: Sean Leonard <[email-masked]>
Date: Wed, 17 Dec 2014 00:37:51 -0800

On Nov 13, 2014, at 12:41 PM, Dale R. Worley <[email-masked]> wrote:

>> From: Sean Leonard <[email-masked]>
> 
>> One reason I wrote it was to deal with the brouhaha on [email-masked]
>> about fragments (so-called “f-components”). XML namespaces don’t use
>> fragments much, but RDF does. This proposal represents one attempt
>> to deal with fragments in a systematic and URN + URI-compatible way.
> 
> That sounds useful.  But given that the brouhaha exists, you need to
> discuss more explicitly that you expect to use these URNs (1) with
> fragment identifiers and/or (2) containing fragment identifiers -- and
> the consequences thereof.  I don't think you have to solve the general
> problem, but since the general problem hasn't been solved, you have to
> show that you've thought through all the aspects that could arise in
> your envisioned use cases.
> 
> (BTW, are fragment identifiers used with XML namespace identifiers?)

Thanks for the continued review—and sorry that I went on IETF hiatus for a few weeks. It happens with the holidays and with coming back from a beautiful tropical island. :)

To answer this question: to my knowledge fragment identifiers are not really used with XML namespace identifiers. Fragment identifiers are used with RDF (nodes). That being said, the XML-based mechanisms for comparing URIs are the same between XML namespaces and RDF (nodes)—both treat the URI as an opaque string and compare for exact equality. Thus the fragment matters in both cases to the extent that it is a different sequence of characters. As a second-order matter, both offer the temptation for an application to dereference the URI to get some XML namespace or RDF-related resource, even though that is not guaranteed or even implied by the relevant specs.

Sean