Re: XML Schemas: Best Practices

[Martin Bryan <mtbryan@sgml.u-net.com>]

>   What if we wanted to extend
>     <Book> by adding elements to the beginning (before <Title>), or in
>     the middle, etc?  We can't do it with this mechanism.

Whats wrong with

    <complexType name="BookTypePlusReviewer">
       <complexContent>
            <extension base="c:BookType" >
                <sequence>
                    <element name="Reviewer" type="string"/>
                    <element name="Title" type="string"/>
                    <element name="Author" type="string"/>
                   <element name="Date" type="year"/>
                   <element name="ISBN" type="string"/>
                 <element name="Publisher" type="string"/>
              </sequence>
           </extension>
       </complexContent>
   </complexType>

It still conforms to the type definition and adds the required new element.
As far as I am aware there is no restriction on you redefining the existing
elements if you need to reorder the elements. (This is the way restrictions
work.)

Martin Bryan