Restriction in XML Schema

[Jay Zhang <jz@intermicstech.com>]

The definition of restriction in XML Schema reads:

 

>A type definition whose declarations or facets are in a
>one-to-one relation with those of another specified type
>definition, with each in turn restricting the possibilities
>of the one it corresponds to, is said to be a restriction.

 

Would this definition make syntactic coincidence unduely
significant?

 

Let me illustrate with an example:

 

Let me define a base type 'fields' as:

 

<complexType name='fields'>
    <sequence>
        <element name='field' maxOccurs='Unbound'/>
    </sequence>
</complexType>

 

would the following derived type have violated the definition
of restriction?

 

<complexType name='myfields'>
    <complexContent>
        <restriction base='fields'>
            <sequence>
                <element name='field' tag='15A'/>
                <element name='field' tag='20'/
            </sequence>
        </restriction>
    </<complexContent>
</complexType>

 

However, if we define base type fields to be an equivalent:

 

<complexType name='fields'>
    <sequence>
        <element name='field' maxOccurs='Unbound'/>
        <element name='field' minOccurs='0' maxOccurs='Unbound'/>
    </sequence>
</complexType>

 

Then the restriction is OK.

 

Please tell me that I misread the definition.

 

Jay Zhang
IntermicsTech, Inc.