RE: Escher could have drawn it (Re: XML Schema and Entities)

[Dylan Walsh <Dylan.Walsh@Kadius.Com>]

> From:	Henry S. Thompson [SMTP:ht@cogsci.ed.ac.uk]
> Sent:	Thursday, June 21, 2001 1:36 PM
> To:	vdv@dyomedea.com
> Cc:	xml-dev@lists.xml.org
> Subject:	Re: Escher could have drawn it (Re: XML Schema and
> Entities)
> 
>XML Schema does not have a notion of document element at all, so in
that
>sense DOCTYPE is not here to stay, I don't think.

How does this work in practice? I am not very familiar with XML Schema.
Lets say somebodies intended XML structure is as follows:

<?xml version="1.0" ?>
<a>
	<b>
		<c />
	</b>
</a>

Does this mean that it is impossible to write a XML Schema where this
document would *not* be valid:

<?xml version="1.0" ?>
<b>
	<c />
</b>

I presume this is not the case, and that <b> and <c> can defined in such
a way that they can only occur in a certain context. In such a case, you
could deduce that <a> is the root element, even if it is not explicitly
marked as such. However, it may be the case that other elements, <x>,
<y> and <z> could also be defined with the same content model as <a>,
and therefore there are 4 possible root elements for a schema valid
document. Is this the case?