MathML expression, conformance, DTD

I'm struggling to understand the role of DTDs in the new
MathML spec. I see:

"A MathML document must be a well-formed XML documents using elements in
the MathML namespace as defined by this specification, however it is not
required that the document refer to any specific Document Type
Definition (DTD) or schema that specifies MathML."
 --
http://www.w3.org/TR/2007/WD-MathML3-20071005/appendixa.html#parsing.wellformed

so far, so good; but then:

"A valid MathML expression is an XML construct determined by the MathML
DTD together with the additional requirements given in this
specification."
 -- http://www.w3.org/TR/2007/WD-MathML3-20071005/chapter2.html#id.2.3.1

I don't understand how to make sense of both of those at the same time.

I wonder if it would be easier to specify conformance w.r.t. the
XML Schema... perhaps something like..

  A MathML expression is an XML element that conforms to the
MathMLExpression element type in the schema.

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

Received on Tuesday, 9 October 2007 20:29:17 UTC