xml-dev - Re: Deriving By Restriction

[ht@cogsci.ed.ac.uk (Henry S. Thompson)]

Lindsey McNerney <lindzer1@yahoo.com> writes:

> I have a complex type that I want to use to derive a
> more restricted complex type, in other words, use one
> structure where five elements are required and
> re-define the structure so that one element is
> optional.  I realize that I could use the 'derivedBy'
> attribute, however I don't want to have to redefine
> all the elements of my original structure, I just want
> to list the one element that has changed.  Is my
> understanding correct that to use derived by
> restriction all the elements of the base type
> structure must be repeated?  If so, is there another
> way to accomplish this?

You can define a type with five elements, one of which is optional,
and define a restricted type based on it which contains only the four
non-optional ones.

You can't go the other way.

In v.1 of XML Schema, there is no way to do this other than by
explicitly including the four required elements in
the restricted type definition.

ht
-- 
  Henry S. Thompson, HCRC Language Technology Group, University of Edinburgh
          W3C Fellow 1999--2001, part-time member of W3C Team
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