utypes: a proposal

[Igor Chilingarian]

Hi Norman,

On Thu, 30 Oct 2008, Norman Gray wrote:

> How about this:
>
>   For each literal value defined in a data model, define as its utype
>   that XPath which would retrieve the literal values from
>   the 'natural' XML serialisation of the data model.
>
> That's all -- beginning and end of proposal.  The following illustrates how 
> this would appear.

Excellent proposal! I wanted to post exactly the same message on the DM list, 
but you were the first! Francois tried to propose this syntax almost two years 
ago for the CharDM but it was rejected by the sub-group, so it never appeared
on the general DM list. As far as I remember, at that time the argument was 
"it is a way too complex".

I don't understand why not to follow this idea. Presently, UTYPEs look like 
"almost-XPath" but not exactly. The differences are: (1) "." instead of "/"; 
(2) no "[]" with additional constraints; (3) no reference to a namespace (this 
seems to change with the latest Francois' proposal).

Since the UTYPEs may be used outside an XML context, the only issue is how to 
deal with namespaces, I mean how to resolve them if there is no explicit link 
to a corresponding XML schema.

With best regards,
 						Igor