Re: How to define <elements> in specifications

* Karl Dubost wrote:
>You mentionned Elements and attributes, do you limit your thoughts to 
>XML languages?  It's a tricky thing. I'm trying to think about 
>something which is a marker (not giving it the name of elements) in a 
>language, etc.

Yes, or more precisely, I limit this to classes of markup languages. As
I pointed out, there are very different kinds of markup languages. One
language might make heavy use of attributes while others are virtually
free of attributes, or the language might model something else, e.g.,
SVG defines properties for many things which you can use both as XML
attributes and in style sheets, and XAML models object hierarchies and
the "elements" are defined in the API specifications.

There are also many different uses of the specifications, as you point
out in your brief reviews, if you don't know much about a format and
look straight at some element definition, you rather want to have some
introductory text that explains what you are looking at than a quick
overview of the features of the element an experienced user might like
to have when looking for the name of a feature he can't remember.

I am more looking for things many of the specifications do in similar
but different way. You found for example that some specifications have
schema fragments as the first thing in such a definition and others
put them at the end. Or many of them use some pseudo-code instead of
schema fragments for similar purposes. Yet specs like P3P, WSDL, XSLT,
and Relax NG, which all do something like that, use different formats.

Some specifications like HTML 4 and XSL 1.0 list attributes defined
elswhere for each element, SVG 1.1 on the other hand does not even
though the markup language is, from a specification point of view,
not very different. So what I am looking at are questions like, is it
useful to list attribute-defined-elsewhere for each element or should
this be done in some index -- or not at all?

There are many other differences, Atom for example uses a lot of RFC
2119 keywords to define how elements may nest, which attributes are
required, etc. while DSig Core explicitly does not do that, or WSDL
and WS-Chor, define the language in terms of attribute information
items, element information items, etc. while others do not refer to
such information items at all.

There are often good reasons for such differences, yet I think there
is potential and need to reduce them.
-- 
Björn Höhrmann · mailto:bjoern@hoehrmann.de · http://bjoern.hoehrmann.de
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Received on Tuesday, 19 July 2005 23:37:35 UTC