Re: The UR* scheme registry, Citing URL/URI specs

Tim Bray (
Fri, 24 Oct 1997 17:08:27 -0700

Message-Id: <>
Date: Fri, 24 Oct 1997 17:08:27 -0700
To: Dan Connolly <>, Keith Moore <>
From: Tim Bray <>
Subject: Re: The UR* scheme registry, Citing URL/URI specs
Cc: Larry Masinter <>,

At 06:11 PM 24/10/97 -0500, Dan Connolly wrote:
>So if the URL/URN distinction is that way, please, PLEASE
>show me! Please give an example where the use of the
>term URN vs URL vs URI in the HTML, HTTP, XML, or RDF
>specs will break things. 

I don't think Dan was asking me, but

1. if the XML spec says URL and somebody sends me a doc with an 
   external reference to urn:ietf:rfc:1661 I probably won't be
   able to resolve it, but at least I have some self-defense because 
   I can make a strong case that it's not a URL, so I can tell the 
   sender he's not XML-conformant.
2. If the XML spec says URI and the same thing happens, then I have no 
   defense, because the sender can say "That's a URN, and a URN is a 
   URI, and the spec says I can give you URIs."  I.e. conformance 
   without interoperability.

I think this qualifies as breakage as a direct result of using URI
rather than URL, but then I'm simple-minded.