DTDs are parts of documents but schemas are paired with documents

I'm still in my first read thru, so I'm not sure how this
impact the rest of the spec, but this looks misleading:

	A well-formed document may have an associated schema, derived
	from one or more XML Schema documents; it may have an
	associated DTD; or it may have no schema, i.e., it is
	``schemaless''.

http://www.w3.org/TR/2000/WD-query-datamodel-20000511/#section-Post-Schema-Validated-Infoset

In XML, a DTD is part of a document. Schemas may be associated
with documents, but they're distinct. In particular,
it's sensible to say "I used document X with schema S1 and
schema S2" where S1 != S2, but it's not sensible to say
"I used document X with DTD D1 and DTD d2" because X's
DTD is part of X. Another way of saying it:
xml-1.0-valid is a one-place predicate over documents;
xml-schema-valid is a two-place predicate over
documents and schemas:

	"An XML document is valid if it has an associated document type
	declaration and if the document complies with the constraints
	expressed in it."

	-- http://www.w3.org/TR/1998/REC-xml-19980210#dt-valid


	"[Definition:]  Throughout this document we use the phrase
	schema-valid loosely to refer to a successful outcome to
	any of the above-listed assessments of an element
	information item with respect to a schema. "

	--
http://www.w3.org/TR/2000/WD-xmlschema-1-20000407/#validation_outcome

-- 
Dan Connolly, W3C http://www.w3.org/People/Connolly/

Received on Monday, 22 May 2000 09:42:42 UTC