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

[Rick JELLIFFE <ricko@geotempo.com>]

AndrewWatt2000@aol.com wrote:
  
> My perception is that XML never was truly a "subset" of SGML.
 
XML was developed as a subset of SGML.  Most of the ISO working group
which looked after SGML were also involved with the creation of XML
(Clark, Kimber, Bosak, also Goldfarb, Peterson, me, and others).  The
correction for SGML came out before XML was finally put as a
recommendation (AFAIR) so there never was a time when XML was not a true
subset of SGML.

Where there were differences,  ISO8879 was corrected specifically to
make sure that XML was indeed a subset. In fact, Charles Goldfarb even
said at one stage "XML *is* the revision of SGML" (debate on the
revision of ISO 8879 had started years before: XML was the embodyment of
that). 

In fact, XML is explicitly part of  ISO 8879, through non-normative
Annex L: XML is used as an example of an "additional requirements"
document--it cannot be normative because the ISO WG thought that W3C was
an appropriate body to create and maintain an industry-lead profile of
an ISO standard.

>From the other way, you can see that there is a non-normative reference
in XML to James Clark's document giving an SGML declaration to handle
XML (in fact, this grew out of Appendix L).  It is non-normative because
you shouldn't need to know ISO 8879 to understand the XML spec.  Some
people want "non-normative" to somehow mean irrelevent material that can
be discarded or discounted whenever convenient. 

XML Schemas do not alter anything w.r.t. XML status w.r.t. SGML.  

Rick Jelliffe

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