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Re: [xml-dev] XML spec and XSD

Tim Bray schrieb am 14.11.2009 um 12:49:06 (-0800):

> The fact that  DTDs were baked into XML 1.0
> is a historical accident.

Given the role SGML seems to have played when XML was drafted, the
inclusion of DTDs rather appears to be a historical inevitability.
Wasn't DTD too useful to be left out?

To continue your oven analogy, wouldn't XML without DTD have been
like raisin cake without raisins?

Or maybe you mean it would have been wise to leave out only those parts
that constrain the structure of the document in terms of elements and
attributes, but not other parts, such as entity declarations?

Also, agreeing to enhance DTD instead of inventing XSD, allowing the
user to define and assign types, might have been an alternative.

I've often heard or read that people wanted an XML notation for the
schema language and were dissatisfied with DTD for this very reason.
However, if you try to process XSD at the XML level, let's say in order
to produce an HTML page to document the notoriously unreadable XSD
syntax, you eventually realize that the language is pretty complicated
and you need a normalized representation of its syntax first. (Which
Saxon provides in the SA and Enterprise versions.)

So yes, it is XML, but no, it is not easily readable, or immediately
useful. And that's why I fail to see the reason why XML syntax was
desired in the first place.

Michael Ludwig

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