W3C home > Mailing lists > Public > www-rdf-logic@w3.org > May 2001

Re: DAML+OIL bug

From: Drew McDermott <drew.mcdermott@yale.edu>
Date: Tue, 22 May 2001 11:23:43 -0400 (EDT)
Message-Id: <200105221523.LAA10912@pantheon-po04.its.yale.edu>
To: www-rdf-logic@w3.org

   [me]
   > In the DAML+OIL example, we have
   > 
   > <rdf:RDF
   >   xmlns:rdf ="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
       ...
   >   xmlns     ="http://www.daml.org/2001/03/daml+oil-ex#"
   > >
   > 
   > The Allegro XML parser claims these are malformed URIs.

   Well, they're perfectly good namespace names, i.e. URI references.
   They work in lots of XML/XSLT/XML Schema software I use.
   The Allegro XML parser is complaining for no good reason.

   >  At first I
   > thought I needed to do some "escape" trickery to get those #'s in, but
   > my second thought was that the Allegro parser is correct.  Shouldn't
   > the #'s just go away?

   No.

   >  Namespaces are not the same as URL + name
   > fragments.

   Actually, they are:

   [[[
   [Definition:] An XML namespace is a collection of names, identified by a
   URI
   reference [RFC2396],
   ]]]

   --        Namespaces in XML
   http://www.w3.org/TR/1999/REC-xml-names-19990114/#dt-namespace
   Thu, 14 Jan 1999 22:24:57 GMT


   [[[
   4. URI References

      The term "URI-reference" is used here to denote the common usage of a
      resource identifier.  A URI reference may be absolute or relative,
      and may have additional information attached in the form of a
      fragment identifier.
   ]]]

Okay, more research has turned up the following, from

http://www.w3.org/Addressing/URL/4_2_Fragments.html

which is a section of 

http://www.w3.org/Addressing/URL/URI_Overview.html

by Tim Berners-Lee:

   The fragment-id follows the URL of the whole object from which it is
   separated by a hash sign (#). If the fragment-id is void, the hash
   sign may be omitted: A void fragment-id with or without the hash sign
   means that the URL refers to the whole object.

So 
xmlns:foo="http://random.org/expl#"

and

xmlns:bar="http://random.org/expl"

use the *same* URI written two different ways, and hence define the
same namespace.  So Allegro's parser should not complain when it sees
the trailing #, although it could discard it.

Thanks.

                                             -- Drew McDermott
Received on Tuesday, 22 May 2001 11:23:46 UTC

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