</sequence>
    </restriction>
  </<complexContent>
</complexType>

 

>From: ht@c... (Henry S. Thompson)

...

> > The definition of restriction in XML Schema reads:
> >
> > >A type definition whose declarations or facets are in a
> > >one-to-one relation with those of another specified type
> > >definition, with each in turn restricting the possibilities
> > >of the one it corresponds to, is said to be a restriction.
>
>Note this is an introductory summary early in the spec.

This is actually Definition 2 in 2.2.1.1. Looks like the official

definition of restriction, unless someone can point to a "more"

official definition. According to this definition, my derivation

'myfields' is in error! I have to rewrite 'fields' as:

 

 

Of course, an elegant semantic definition we all prefer can be

( actually in "an introductory summary early in the spec"):

"...the values represented by the new type are a subset of the values

represented by the base type ..."

 

But this definition is not computationally feasible! It got to be

NP-hard to compare the language sets defined by two schemas.

 

I am glad that you brought up the issue of Unique Particle

Attribution constraint. It is also a computational feasibility

challenge to enforce. Finding that one instance element looks

NP-Complete to me again.

 

I expect syntax-oriented, but more elaborate definitions

dictated by standards. Where is it? Did I lose a page in my book? :-)

 

Jay Zhang

IntermicsTech, Inc.