XML Schema 1.1 requirements : extensible enumerations

I would like to submit the requirement for extensible enumerations to
XML Schema 1.1. This requirement has its origins in our work in the
OSS through Java Initiative. See: http://java.sun.com/products/oss/ In
our API development efforts, we have identified extensibility
patterns, where variability is encapsulated. Java interfaces are
isomorphic to XML messages through a language binding. (See JSR 144)

There have been cases, where we have needed enumerations that can be
extended. There are ways to support extensible enumerations elegantly
in Java. However, we have struggled to find a reasonable way to do
this in XML Schema. We settled on working around the problem in XML
Schema using substitution groups. This approach replaces the full set
of enumeration values, whenever it needs to be extended by a
subtype. An approach that supports extension and restriction of
enumerations similar to complexTypes would be much better.

Ben

Received on Monday, 25 March 2002 11:30:45 UTC