Re: To DTD or Schema? Issues for Transformiix, Soblotron etc

Subject: Re: To DTD or Schema? Issues for Transformiix, Soblotron etc
From: David Carlisle <davidc@xxxxxxxxx>
Date: Fri, 5 May 2000 12:43:49 +0100 (BST)
> Hopefully someone can offer me some guidance here about the
> validity of using schema's versus DTD'

> ...
> but David seems to be saying below that we should go DTD
> based. Schemas look a lot easier to handle, but if we can't do our
> XSLT processing based on them maybe we need to step back.

`DTD' has a specific meaning, the DTD syntax is defined in the XML spec
and its semantics is inherited from SGML.

`Schema' in this context means lots of different things, there are
various schema proposals around to have some extended DTD functionality
using XML instance syntax. None so far has been made into an official
W3C recommendation.

In particular there is the W3C Schema proposal, and once that becomes a
W3C recommendation I'd expect that XSLT would be updated to support some
of the schema datatypes in the way that it currently has support for
id which are a DTD feature.

There are other proposals, including the syntax that you used which is a
microsoft language. It's not that that language is particularly bad, but
you can't call it a bug in an XML application such as transformiix if it
has no knowledge of that particular language.

Many XSL implementations may be customised to work with different XMl
parsers, and if you use MSXML parser to parse your document it will
read the microsoft schema and add the attribute defaults specified there
so they'll be seen by following applications. But you can't expect any
other XML parser to do that. Whether or not this reliance matters in
your context I can't say (it would matter to me as I so rarely use
a Microsoft machine:-).

If you are using MSXML anyway the obvious XSLT engine to use is one
you didn't mention, namely the one built into the preview `web-release'
of MSXML3 from Microsoft, which is fairly compliant (but incomplete,
currently) to the W3C specs, unlike the XSL built into the MSXML shipped
with IE5 which is famously (on this list at least) non compliant.

David


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