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RE: Possible issue: XML DOCTYPE declaration -- should the PUBLIC identifier be a URN?

From: Thompson, Bryan B. <BRYAN.B.THOMPSON@saic.com>
Date: Wed, 8 Oct 2003 12:15:06 -0400
Message-Id: <D24D16A6707B0A4B9EF084299CE99B390674D4BF@mcl-its-exs02.mail.saic.com>
To: Paul Grosso <pgrosso@arbortext.com>, "Thompson, Bryan B." <BRYAN.B.THOMPSON@saic.com>, www-tag@w3.org
Cc: "Bebee, Bradley R." <bebeeb@US-McLean.mail.saic.com>, Guy.A.Lukes@frb.gov


I choose the words '"as if" it were a universal resource name' to indicate
that it had similar semantics, not that it was, in fact, conformant to the
URN specification.  Thanks for the [2] and [3] references, but I still think
that this might be clarified, e.g., in the XML specification.  Basically
'catalog' approach and the URN approach are partially overlapping.  It would
be nice to see this addressed.


-----Original Message-----
From: Paul Grosso [mailto:pgrosso@arbortext.com] 
Sent: Wednesday, October 08, 2003 10:55 AM
To: Thompson, Bryan B.; www-tag@w3.org
Cc: Bebee, Bradley R.; Guy.A.Lukes@frb.gov
Subject: Re: Possible issue: XML DOCTYPE declaration -- should the PUBLIC
iden tifier be a URN?

At 10:16 2003 10 08 -0400, Thompson, Bryan B. wrote:

>I just noticed that the XML 1.0 Recommendation (Second edition) does 
>not state a requirement that the public identifier in a DOCTYPE 
>declaration must be a URN, e.g.:
>-- snip from http://www.w3.org/TR/REC-xml#NT-ExternalID --
>[Definition: In addition to a system identifier, an external identifier 
>may include a public identifier.] An XML processor attempting to 
>retrieve the entity's content may use the public identifier to try to 
>generate an alternative URI reference. If the processor is unable to do 
>so, it must use the URI reference specified in the system literal. 
>Before a match is attempted, all strings of white space in the public 
>identifier must be normalized to single space characters (#x20), and 
>leading and trailing white space must be removed.
>-- end snip --

 . . .

>So it is pretty clear that the public identifier is not a URN per 

Correct, it does not have to be a URN.  It has to be a public identifier
whose syntax is defined in the XML spec [1].

>At the same time, it is being used "as if" it were a universal resource 

Huh?  Says who, where, and what does this mean?  The paragraph from the spec
that you quote above defines what may be done with a public identifier, and
"use the public identifier [in some unidentified way] to try to generate an
alternative URI reference" does not mean "use as if it were a URN" to me.

For example, see the various OASIS Catalog specs [2,3] if you are not
familiar with how public identifiers are and have been used for over a

>and the XML processor is encouraged to identify a URI that may be used 
>address the XML grammar declared by the DOCTYPE declaration.

I'm not sure I understand the issue here at all.


[1] http://www.w3.org/TR/REC-xml#NT-PubidLiteral
[2] http://www.oasis-open.org/specs/tr9401.html
Received on Wednesday, 8 October 2003 12:15:20 UTC

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