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Re: Possible issue: XML DOCTYPE declaration -- should the PUBLIC iden tifier be a URN?

From: Paul Grosso <pgrosso@arbortext.com>
Date: Wed, 08 Oct 2003 09:55:20 -0500
Message-Id: <>
To: "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

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 RFC2396.

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 name

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 already 
familiar with how public identifiers are and have been used for over a decade.

>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
[3] http://oasis-open.org/committees/entity/specs/cs-entity-xml-catalogs-1.0.html
Received on Wednesday, 8 October 2003 10:58:57 UTC

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