Norman Walsh wrote:
> / James Clark <> was heard to say:
> | Right. We could have a restriction on combine="group" that you can't use it
> | in a way which makes order significant (eg combining two <element>
> | patterns). On the other hand that would rule out using combine="group" to
> | provide functionality similar to derivation of complex types by extension in
> | XML Schema (adding things on to the end of a content model).
>
> Making order insignificant would be nice, but I think it would be a
> mistake to lose the ability to mutate content models this way.
We do not need "combine" for mimicking "derivation by extension".
Here is a rewrite of an example of "derivation by extension" in
XML Schema Part 0.
<grammar>
<start>
<element name="dmy">
<element name="uk">
<ref name="UKAddress"/>
</element>
<element name="us">
<ref name="USAddress"/>
</element>
</element>
</start>
<define name="Address">
<element name="name"><anyString/></element>
<element name="street"><anyString/></element>
<element name="city"><anyString/></element>
</define>
<define name="USAddress">
<ref name="Address"/>
<element name="state"><anyString/></element>
<element name="zip"><anyString/></element>
</define>
<define name="UKAddress">
<ref name="Address"/>
<element name="postcode"><anyString/></element>
<attribute name="exportCode"><anyString/></attribute>
</define>
</grammar>
Cheers,
Makoto
