Re: [xml-dev] Wikipedia on XML

[rjelliffe@allette.com.au]

> 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.

Strictly speaking, a well-formed document with no DTD conforms to SGML
too: it is a "fully-tagged" "tag-valid" document.
 http://www1.y12.doe.gov/capabilities/sgml/wg8/document/1929.htm

> The relationship between SGML and XML is really only meaningful
> for XML documents with actual DTDs.

Help! Liam is stuck in a time warp in 1995!

> 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.

There is no assumption that there is a DTD for an SGML document either,
since the 1997/1998 changes to cope with SGML.

"A conforming SGML document must be either a type-valid SGML document, a
tag-valid SGML document, or both.  Note: If there is a document type
declaration, the instance can be parsed with or without reference to it."

Cheers
Rick Jelliffe