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   RE: DTD invented by Microsoft?!

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  • From: "Ingo Macherius" <Ingo.Macherius@TU-Clausthal.de>
  • To: akirkpatrick@ims-global.com
  • Date: Wed, 25 Jun 1997 19:53:05 +0000

> Could someone explain what "instance syntax for type definitions"
> means. Thanks!

	I am aware this is a beginner's question. Is xml-dev the right place
	to answer ? If not, where is the place for such Q/A ? 

In valid XML there are two distinct parts of a document, the DTD and 
the "document instance". Both serve different purposes. The 
"instance" is the marked up text the user produces. (So any valid 
HTML page is an "instance" of the HTML DTD). The tags allowed in the 
instance are declared in the DTD using a different syntax.

The term "instance syntax for type definitions" means, that the same 
syntax is used for both DTD and instance. Compare:

	<!doctype aaa [
		<!element aaa	(bbb+)		> <!-- This is XML DTD syntax -->
		<!element bbb	(ccc*)		>
		<!element ccc	(#PCDATA)	>


	<doctype>					<!-- This is the same structure	-->
		<element>				<!-- expressed in instance syntax -->
			<name>aaa</name>	<!-- (example only, invalid)	--> 
			<model></rni type="PCDATA"></model>

Using the second case there has to be a mechanism to tell 
meta-structure-defining tags (<element>, <doctype>, ...) from 
user-defined ones, e.g.	
	1. namespaces (proposed mechanism for XML)
	2. reserved attributes (like the current XML-Link draft)
	3. reserved names (like with HTML)
	4. processing instructions (shudder)
	5 ...

Q: Has Microsoft published the intended syntax for "Schemata"  
(the MS name for "marked up" DTD) to the public ? I can't find the 
link, help is welcome.

Ingo Macherius // L'Aigler Platz 4 // D-38678 Clausthal-Zellerfeld
mailto:Ingo.Macherius@tu-clausthal.de    http://www.tu-clausthal.de/~inim/
Information!=Knowledge!=Wisdom!=Truth!=Beauty!=Love!=Music==BEST (Frank Zappa)

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