Why XML data typing is hard (was Re: Internal subset equivalent in new schema proposals?)

[len bullard]

david at megginson.com wrote:
> 
> I'm not suggesting that a set of simple XML data-typing constraints
> cannot be helpful -- if you're building a database only of Norwegian
> city names, you know that you don't have to deal with Han or Kanji
> (unless, of course, you do such a good job that you decide to
> commercialise your system) -- but coming up with data-type constraints
> that both useful and generalised enough for all XML users across all
> of the major Locales and all of the Unicode character repetoire is
> *very* difficult.

Yes.  I think you have presented good arguments why a declaration for 
conventional/primitive datatypes should not be in XML 1.0.  However, 
such a declaration has been asked for and is useful.  For example, 
languages such as VRML have to declare such types to ensure the 
efficiency of the application language.  Applications such as 
relational databases have to declare datatypes to insure integrity.  
A common reference for these will be of value to the application 
language communities that require them and intend to use SGML/XML 
for their schema.  Given that XML is a product of the W3C, it is 
the responsibility of the W3C to produce a product to support this 
requirement.  A separate reference would be ideal.

And sooner rather than later.

len

xml-dev: A list for W3C XML Developers. To post, mailto:xml-dev at ic.ac.uk
Archived as: http://www.lists.ic.ac.uk/hypermail/xml-dev/
To (un)subscribe, mailto:majordomo at ic.ac.uk the following message;
(un)subscribe xml-dev
To subscribe to the digests, mailto:majordomo at ic.ac.uk the following message;
subscribe xml-dev-digest
List coordinator, Henry Rzepa (mailto:rzepa at ic.ac.uk)