xml-dev - Re: 25 Feb Structures Questions

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

Michael Anderson <michael@research.canon.com.au> writes:

> "Henry S. Thompson" wrote:
> 
> >  Michael Anderson <michael@research.canon.com.au> writes:
> >
> >  > 2. Also with restrictions, if attributes of elements are omitted do they
> >  > default to the standard default or the values defined in the base type
> >  > definition?  Or is it an error to omit attributes previously defined in
> >  > the base?
> >
> >  Do you mean if they are omitted in instances?  If the derived type
> >  definition has defaults, they will get used.
> 
> I mean in the Schema document.  So for example, based on the Primer example:
> (take note of the attribute minOccurs)
> 
> <complexType name="World-Address" >
>   <element name =  "name"   minOccurs ="0" maxOccurs="*" />
>   etc.
> </complexType>
> 
> <complexType name="US-Address" base="ipo:World-Address"
>               derivedBy="restriction"
>   <element name = "name"  type="string" />
>   etc.
> </complexType>
> 
> What now is the value of minOccurs for the "name" element in the
> type "US-Address"?  Is it 0 as that was defined in the base type, or
> is it 1 which is defined as the default for elements (section 4.4.2
> of Part 1:Structures)?  0 or 1?

Sorry this isn't well explained, we changed this area of the design
very close to publication, and a complete description was not provided 
in time.

The new design for complex type definition by restriction is that you
supply a complete type definition which you _assert_ is a restriction, 
and this is checked at schema processing time.  No copying from the
base type definition is performed.  This is different from simple type 
definition by restriction, were unmentioned facets _are_ copied down, as 
it were.

ht
-- 
  Henry S. Thompson, HCRC Language Technology Group, University of Edinburgh
          W3C Fellow 1999--2001, part-time member of W3C Team
     2 Buccleuch Place, Edinburgh EH8 9LW, SCOTLAND -- (44) 131 650-4440
	    Fax: (44) 131 650-4587, e-mail: ht@cogsci.ed.ac.uk
		     URL: http://www.ltg.ed.ac.uk/~ht/

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