Lists Home |
Date Index |
All things are fuzzy to some extent, but XML is far less fuzzy than
most. There is a reasonably well-written specification that defines
precisely what is and is not XML. In fact, the very first sentence of
the specification is:
The Extensible Markup Language (XML) is a subset of SGML that is
completely described in this document.
A little later we have:
Extensible Markup Language, abbreviated XML, describes a class of
data objects called XML documents and partially describes the
behavior of computer programs which process them. XML is an
application profile or restricted form of SGML, the Standard
Generalized Markup Language [ISO 8879]. By construction, XML
documents are conforming SGML documents.
There's not much wiggle room here. Certainly there are things in the
universe that are not XML, and many of them are useful. But that
doesn't make them XML.
Read the first sentence again. It says "completely described". This
isn't a beginning. This isn't one part of the XML trinity. It is XML,
and nothing else is XML. XML is often processed with various tools,
and perhaps some of these tools can be made to process other non-XML
formats, but that doesn't make those formats XML.
Elliotte Rusty Harold
Effective XML (Addison-Wesley, 2003)