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Re: Namespaces and validation

From: Dan Connolly <connolly@w3.org>
Date: Wed, 05 Aug 1998 16:55:17 -0500
Message-ID: <35C8D4C5.1B27@w3.org>
To: Klaus Malorny <Klaus.Malorny@knipp.de>
CC: xml-names-issues@w3.org
Klaus Malorny wrote:
> at first I have to say that I think that namespaces are a great idea
> as they greatly improve the useability of XML when creating complex
> documents including formulas, graphs and other embeded objects. On the
> other hand I was very disappointed to see that a major benefit of XML
> was given up with this specification: The capability to validate the
> document based on DTDs, without knowledge of the semantics of the
> tags. Instead, one can create a document like this:
> 
> <?xml version="1.0"?>
>   <!-- both namespace prefixes are available throughout -->
>   <bk:book xmlns:bk='urn:loc.gov:books'>
>       <bk:title>Cheaper by the Dozen</bk:title>
>       <td xmlns='http://www.w3.org/TR/REC-html40'>This is some
> text</td>
>   </bk:book>
> 
> 
> which  - I hope you will agree - does not make any sense, since the
> <td> tag should never appear outside of a html table.

With respect to XML 1.0 validation, that document behaves just like:

<?xml version="1.0"?>
   <!-- both namespace prefixes are available throughout -->
   <bk:book>
       <bk:title>Cheaper by the Dozen</bk:title>
       <td>This is some
 text</td>
   </bk:book>

i.e. it's well-formed, but not valid.

We expect namespaces to integrate more with future document
structuring mechanisms ("schemas") than with XML 1.0 DTDs.

> Even if you don't include any rules concerning the validation of
> documents which use namespaces, it would be a good idea to add some
> comments about your future plans regarding this topic.

That's a good idea for the "status of this document" section,
and for the XML Activity statement, which needs updating;
stay tuned to:

	http://www.w3.org/XML/Activity

We tried including a sort of forward reference to schemas
in the body of previous drafts, but folks found that confusing and
misleading too.

-- 
Dan Connolly
http://www.w3.org/People/Connolly/
Received on Wednesday, 5 August 1998 17:54:10 UTC

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