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RE: DTD for protocol-03?

From: Martin J. Dürst <mduerst@ifi.unizh.ch>
Date: Tue, 7 Oct 1997 13:15:53 +0100 (MET)
To: Yaron Goland <yarong@microsoft.com>
cc: "'ejw@ics.uci.edu'" <ejw@ics.uci.edu>, "'Terry Allen'" <tallen@sonic.net>, "'w3c-dist-auth@w3.org'" <w3c-dist-auth@w3.org>
Message-ID: <Pine.SUN.3.96.971007123618.7026i-100000@enoshima>
On Mon, 6 Oct 1997, Yaron Goland wrote:

> DTDs are NOT necessary for XML and in fact are seen as being deprecated
> by many parts of the XML community.

... while they are highly valued by other parts of that community :-).


> Furthermore the DTD syntax is not
> well known amongst the HTTP community, of which DAV is a member, while
> BNF is.
> 
> Given that providing a DTD is not necessity for XML and that we will
> still have to provide our current syntax I propose that we add DTDs, as
> an appendix, to the final draft. Until we reach that final draft, there
> is little point in having to maintain two sets of definitions.

A DTD is indeed not necessary for many kinds of processing of XML,
due to certain enhancements in XML that where not present in SGML originally.
However, a DTD not only provides a written definition of an XML
application, it also allows to use tools to a much greater extent
than a BNF. With a DTD and a piece of XML, you can check whether
the XML conforms to the DTD with tools that are both publicly
available or commercial.

Also, it is very clear that a DTD is the official way to define
some XML syntax. The problem is that the expressibility of a
DTD is not exactly the same as that of a BNF. There are some
cases that are easier to specify in a DTD, and others that are
easier to do in a BNF. But having two different specifications
in the WEBDAV spec is of course not desirable. That's why I
think it makes a lot of sense to try to start with a DTD
early on. We don't need to repeat the mistakes Netscape made
with HTML.


Regards,	Martin.
Received on Tuesday, 7 October 1997 07:19:23 GMT

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