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RE: [xsl] XSLT Architecture: Next Step


Subject: RE: [xsl] XSLT Architecture: Next Step
From: Didier PH Martin <martind@xxxxxxxxxxxxx>
Date: Fri, 04 Jul 2003 08:02:04 -0400

Hello Bill,

Bill said:
Actually XML is very much a language; i.e., it has a well defined set of
terminal symbols and a grammar describing which strings are acceptable as
strings of the language. Obviously there are a number of parsers out there
that utilize this language definition in order to parse these strings.

I know I'm nit picking, but ...

Didier replies:
I am sorry Bill, but XML is not a language but a meta language. More
specifically it is a set of syntax rules but it lacks any semantics or
element structure. As you know, a fully qualified languages does include
syntax, semantics and structure. The semantics and the structure are not
provided by XML but by the designer of the XML based language. Using
languages like DTD, schema, relax, etc... to define the keywords and the
structural rules. XML is an empty shell, it doesn't provide you the keywords
(i.e. the elements and attributes) you get in any well formed language.

 To transform an XML set of syntax rules into a language you need to add the
keywords (i.e. the elements and the attributes) and the structural rules
(i.e. one or several occurrences, what kind of element is allowed under that
one, what are the attributes attached to a particular element, what kind of
data content is allowed for a particular element, etc...).

Thus, XHTML is a language, its structural rules are defined and elements and
attributes specified. XML, per se, is the meta language used to create
XHTML.

Cheers
Didier PH Martin
http://didier-martin.com



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