Re: [xml-dev] Wikipedia on XML

[Liam Quin <liam@w3.org>]

On Fri, Aug 21, 2009 at 06:09:58PM -0700, Kurt Cagle wrote:
> Keep in mind audience here. I'd be inclined rather to indicate that an XML
> document is a valid SGML document as well,

Strictly speaking, any valid (i.e. DTD-valid) XML document is also
valid SGML document.

> that for this reason there is an
> implicit assumption that a DTD exists for any created XML document type, but
> that current usage is increasingly to keep such DTD's implicit in favor of
> more explicit definitions by other schemas.

The relationship between SGML and XML is really only meaningful
for XML documents with actual DTDs.  It's not usefully the case that
there's an implicit document type declaration, and although the
vague and all-encompassing SGML definition of a document type
definition might be said to apply to any document, such a remark
would merely be vacuous sophistry.  There's no assumption that there
is a DTD for any XML document.

As for (per ERH) the DTD modifying the infoset, strictly speaking
the XML infoset specification gives us a way to describe the
result of parsing an XML document, and since DTD processing happens
as part of that process, there's no modification... although
maybe I'm being overly pedantic, as it's certainly true you can
end up with different results if you parse the same XML docuent but
with or without its DTD.  Just as you can if you use or don't use
a W3C XML Schema (XSD) thta supplies default content, for example.

Best,

Liam


-- 
Liam Quin, W3C XML Activity Lead, http://www.w3.org/People/Quin/
http://www.holoweb.net/~liam/ * http://www.fromoldbooks.org/