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Re: DTD and schema - what's the difference?

From: Ron Woodall <nor@htmlcompendium.org>
Date: Fri, 10 Jan 2003 09:57:10 -0500
Message-Id: <4.3.1.20030110094618.01c27860@pop.synapse.net>
To: www-html@w3.org

Hi:

         Thank you for the several who responded to my query. I'm 
addressing these comments. "through confusion comes understanding"

>In terms of purpose, none: either can be used for exactly the same job, to 
>define the structure of an XML document.
>
>Otherwise, lots. In particular, XML Schemas are themselves written in XML, 
>with all that implies.

         What then is the function of an XML DTD as compared to an XML 
Schema as compared to an SGML DTD or are they synonymous? As near as I can 
figure XML DTDs and SGML DTDs function as "page interpreters" whereas the 
XML Schema deals with XML "structure?"


and ...

>Whereas XML DTDs are *part* of XML.  I believe the main difference is
>that XML reduced the expressive power of SGML DTDs and XML schemas adds
>back a lot of that power but in different directions (e.g providing
>data type information).  However, the only way to properly answer the
>question is for the questioner to go and read the source documents.

         I've spent the last month and a half reading the documents and 
still can't seem to cobble together an answer. Is there a specific document 
that will provide me with a comparison?

         Thanks for the help.

         Ron Woodall

---------------------------------------
Ron Woodall
nor@htmlcompendium.org

The Compendium of HTML Elements
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Received on Friday, 10 January 2003 09:56:58 GMT

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