> >In other words, deriving from Address changes what is allowed by a
reference
> >to Address.
>
> This is true, but can be easily mimicked as below. Basically, we only
have
> to introduce another named pattern.
That's a nice trick. This does require the author of the invoice schema to
have the foresight to introduce the double indirection
Address/AddressForReference. On the other hand, even combine="group"
requires the author to have the foresight to introduce the Address
definition.
> >allow a postCode. Derivation by extension in XML Schema supports this.
In
> >RELAX NG, combine="group" provides similar functionality.
>
> You have overshadowed the original definition of "Address"; in other
words, postCode
> has become mandatory in your example. I think that this is very different
from
> what people would expect.
I don't think anybody would be surprised that:
<define name="Address" combine="group">
...
</define>
overshadows the original definition of Address.
James
