XML Schema: enumeration 'value' subtyping

I would like to hang in a new thread as a newbie. I understand that
enumeration represents an enumerated type supported on attributes only.
My/our requirement is now *not* only the reduction of list of permitted
values *but* to subtype one (ore more) specific enumeration values, like
EN-us, EN-uk, EN-aus, ... meaning us-english, uk-english,
australian-english, ... Here is an example:

<simpleType name="languageCode" base="string"> 
  <enumeration value="DE"/> 
  <enumeration value="EN"/> 
  <enumeration value="FR"/> 
  <enumeration value="ZW"/> 
</simpleType> 

Example solution with a (very probably incorrect) syntax invented by myself:

<specializedType 
 name="languageSubCode" source="simpleType" deriveBy="extension"> 
  <group ref="EN"> 
    <enumeration value="US"/ >    <!-- Remark: means EN-US -->
    <enumeration value="EN-UK"/>  <!-- Remark: means EN-UK -->
    ...
  </group>
</specializedType> 

We have quite some experience and practice with this type in a national
geodata description and transfer standard, called 'INTERLIS'. The advantage
is, that we can define object- and/or codelists at national/international
level (i.e. landcover, vegetataion types, building or street classnames) and
allow then cantons/admin.regions to make a (hierarchical) subdivision of
this enumeration. This ensures compatibility trough structural polymorphism
down to the data integration level.

What do the XML schema experts mean? Is tihs possible/feasible in XML
Schema?

-- Stefan Keller
______________________________________________________________________
Stefan F. Keller                  INTERLIS.net: http://www.gis.ethz.ch
Eidg. Vermessungsdirektion          Directorate of cadastral surveying
Bundesamt fuer Landestopographie          Federal Office of Topography
Seftigenstrasse 264                           Phone (+41)-31 963 22 44
CH-3084 Wabern (Switzerland)                    Fax (+41)-31 963 22 97
E-Mail: mailto:stefan.keller@lt.admin.ch  Web: http://www.swisstopo.ch
______________________________________________________________________
- Did you already see the article  "INTERLIS 2 - The missing link?" in
GEOEurope May 2000 (http://www.geoplace.com/ge/2000/0500/0500in.asp) ?

Received on Wednesday, 19 July 2000 07:51:02 UTC