XSchema Spec, Sections 2.0 and 2.1 (Draft 1)

John Cowan cowan at locke.ccil.org
Mon Jun 8 20:02:50 BST 1998

Chris Maden wrote:

> The biggest problem with DTDs (IMO) is that they conflate definitions
> for a class of documents with definitions for a single document
> instance.  A schema should try, as cleanly as possible, to refer only
> to the *class* of documents, and leave entities out of it.  After
> XSchema is successful, then we can move on to tackle a new and better
> syntax for entity declaration.

I concede that many, perhaps most, general entities are document
specific, but not all.  Consider the MIXED element from the
my early drafts of XSchema itself.  The form

	<MIXED> <REF .../> <REF .../> ... </MIXED>

declared #PCDATA-and-element content, whereas "<MIXED/>" declared
#PCDATA-only content as a degenerate case.  The DTD could have declared
(though actually it didn't) <!ENTITY PCDATA "<MIXED/>"> to allow
people to write "&PCDATA;" in XSchemas as a better-documented
version of "<MIXED/>".

Surely this entity would be worthy of declaration in the XSchema

> Now, it may be that the "Entity" element is only intended for use
> within the schema.  If so, great, but I think the name should reflect
> that.  Maybe call it "module"?

No, not at all.  There is no XSchema equivalent of parameter entities.
John Cowan	http://www.ccil.org/~cowan		cowan at ccil.org
	You tollerday donsk?  N.  You tolkatiff scowegian?  Nn.
	You spigotty anglease?  Nnn.  You phonio saxo?  Nnnn.
		Clear all so!  'Tis a Jute.... (Finnegans Wake 16.5)

xml-dev: A list for W3C XML Developers. To post, mailto:xml-dev at ic.ac.uk
Archived as: http://www.lists.ic.ac.uk/hypermail/xml-dev/
To (un)subscribe, mailto:majordomo at ic.ac.uk the following message;
(un)subscribe xml-dev
To subscribe to the digests, mailto:majordomo at ic.ac.uk the following message;
subscribe xml-dev-digest
List coordinator, Henry Rzepa (mailto:rzepa at ic.ac.uk)

More information about the Xml-dev mailing list