Re: Difference for attribute values

James Clark wrote:

> Let's consider this in terms of the grammar I posted.  If we added
> <difference> then the unrestricted grammar for pattern would simply get
> another choice:
> 
>   | <difference> pattern pattern </difference>

I think that this is too much.  In my understanding, your proposal 
allows: 

<difference>
<list><oneOrMore><data type="xsd:integer"/></oneOrMore></list>
<list><oneOrMore><data type="xsd:negativeInteger"/></oneOrMore></list>
</difference>

As for validation, this is not a problem.  But I very much hesitate 
to introduce this compliacted (seemingly compliacted at least) feature.  
Any strong reasons to introduce it for V1?   I think that this feature 
will intimidate developers.

> It might be simpler to disallow <text/> in
> <list> altogether.

Agreed.

> If we allow <not/>, then
> 
> <not> p </not>
> 
> should be short for
> 
> <difference> <data type="string"/> p </difference>
> 
> so that <not/> works inside <list>

I would propose to introduce 

<not type="...."/><value .../> <value .../> ...</not> 

Probably, we need inheritance of the type attribute as well.

Cheers,

Makoto