[dsdl-discuss] Re: Three debatable features for Part 7

Murata-san

> This mail suggests three features for Part 7. If we introduce all of
> them, Part 7 will become difficult to develop but become more useful.
> How do you feel?
>
> 1) Kernel and Hull
>
> Martin Duerst introduced kernels and hulls in W3C TR "A Notation
> for Character Collections for the WWW" (2001).
>
> http://www.w3.org/TR/charcol/#Kernels

> We can borrow this idea. Suppose that a schema references to a
> character repertoire description consisting from a kernel and hull.
> If some character in an instance document does not belong to the hull,
> this document is invalid. On the other hand, if some character in an
> instance document does not belong to the kernel, we have warning
> message.

Amajor problem with the Duerst proposal is it lack of identifiable objects.
It does not name collections, and only allows named collections to be
identified by URL. It would appear that you can next references
indefinitely, but there are no rules re conflict resolution. This is OK with
a simple add-only model, but not if you allow exceptions to rules (e.g.
<range>A-Z</range><except>AEIOU</except>

> Even if we do not borrow this idea, Schematron (as a host language) can
> mimic it by using two Schematron rules (one for the kernel
> and another for the hull). However, RELAX NG or DTD do not have this
> option.

Why can't RELAX handle it, providing we tell it that the language it is
defined in is DSDL7? I thought RELAX allowed any set of datatypes to be
applied, and connot see why you can't apply named character sets as a
datatype of a specified kind? (Is there any restriction that prohibits
multiple datatypes being defined for an element in different environments?)

Martin Bryan

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