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From: Leslie Daigle (ThinkingCat) <ldaigle@thinkingcat.com>
Date: Wed, 11 Feb 2015 17:20:55 -0500
Message-ID: <54DBD5C7.1090200@thinkingcat.com>
To: public-web-and-tv@w3.org
On the question of whether GGIE should talk of using URIs or URNs, I 
suggest that the best approach is to use the broader form "URI" unless 
or until it becomes clear that a URN, as defined in the IETF standards, 
is what is needed.  Full disclosure: I chaired the IETF WG that produced 
the URN specifications 15 years ago now; I have biases!

A bit of background:

Uniform Resource Identifiers (often used interchangeably with URL, 
Uniform Resource Locator), have a syntax defined in RFC 3986 [1].  The 
syntax evolved from the original URL specification for the Web and 
includes particular support for hierarchy authorities, fragments and 
queries.    As should be familiar to everyone here, URIs are divided 
into different "schemes", and each scheme specifies details of syntax 
and determines the semantics of using the identifiers.

URN syntax was originally defined (RFC 2141, [2]) to conform to URI 
syntax -- as a URI scheme.  However, fragments and queries were 
specifically set aside:   there wasn't a clear way to define location 
(fragments of documents, or queries in systems) in an identifier system 
that was meant to be location-independent (naming).

I have chosen my verb tenses carefully in that last paragraph.  There is 
current work in the IETF (URNBIS WG [3]) to determine whether or not 
there is a better clarity on how to apply fragments and queries in URNs 
(globally, or whether to permit them on a per-namespace basis), as part 
of bringing the URN specifications up to date.

URNs are divided into individual "namespaces" -- the definition of a 
namespace includes the syntax for carrying identifiers within the URN, 
and provides some background to explain the use of the resulting names 
(to address uniqueness, permanence).

On the whole, I think it would be best to determine what the identifiers 
are meant to do and how they are going to be used before figuring out 
whether they are URIs or should be part of a URN namespace.


[1] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform Resource 
Identifier (URI): Generic Syntax", STD 66, RFC 3986, January 2005, 

[2] Moats, R., "URN Syntax", RFC 2141, May 1997, 

[3] https://datatracker.ietf.org/wg/urnbis/charter/


Leslie Daigle
Principal, ThinkingCat Enterprises
Received on Friday, 13 February 2015 12:27:47 UTC

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