xml-dev - Re: "XML is a subset of SGML" - True or False?

[richard@cogsci.ed.ac.uk (Richard Tobin)]

In article <e8.68b6a1a.26908d3a@aol.com>,  <AndrewWatt2000@aol.com> wrote:

>My perception is that XML never was truly a "subset" of SGML.

[I'm not an SGML expert, so don't take this as the last word on the
subject.]

It *is* intended that XML be a subset of SGML, in the sense that a
valid XML document is also a legal (? I'm not sure what the right SGML
term is) SGML document.  Furthermore, the "Web SGML" additions to
SGML, which you can find at

  http://www.ornl.gov/sgml/sc34/document/0029.htm

extend SGML to allow (among other things) DTD-less SGML documents
provided they are fulled tagged, so that merely well-formed XML
documents can be legal SGML-as-amended-by-TC2.

>Similarly, XML is case sensitive whereas SGML is not.

I believe this can be controlled by the SGML declaration; an SGML
declaration appropriate for XML has been written.

>The secondary part of my question relates to the implications of XML Schema 
>for the assertion that "XML is a subset of SGML". As far as I am aware SGML 
>has no such feature.

Quite so.  Only XML 1.0 itself is a subset of SGML.  But note that
documents validated by schemas, and indeed the schemas themselves, are
still legal SGML documents.  Schemas don't add any new syntax.

-- Richard
-- 
Spam filter: to mail me from a .com/.net site, put my surname in the headers.

"The Internet is really just a series of bottlenecks joined by high
speed networks." - Sam Wilson

***************************************************************************
This is xml-dev, the mailing list for XML developers.
To unsubscribe, mailto:majordomo@xml.org&BODY=unsubscribe%20xml-dev
List archives are available at http://xml.org/archives/xml-dev/
***************************************************************************