Re: Language Theorie concerning XML Schema (heavy, at least to me)

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

I'll answer a simple question which I understand, and which I _think_
is what you're asking.

The following XML document is valid:

<!DOCTYPE root [
<!ELEMENT root (a|x)>
<!ELEMENT a (b|y)>
<!ELEMENT b (c|z)>
<!ELEMENT c EMPTY>
]>
<root><a><b><c/></b></a></root>

Note it contains no declarations for the elements x, y and z.

The corresponding schema document successfully validates the same
instance:

<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema";>
 <xs:element name="root">
  <xs:complexType>
   <xs:choice>
    <xs:element ref="a"/>
    <xs:element ref="x"/>
   </xs:choice>
  </xs:complexType>
 </xs:element>

 <xs:element name="a">
  <xs:complexType>
   <xs:choice>
    <xs:element ref="b"/>
    <xs:element ref="y"/>
   </xs:choice>
  </xs:complexType>
 </xs:element>

 <xs:element name="b">
  <xs:complexType>
   <xs:choice>
    <xs:element ref="c"/>
    <xs:element ref="z"/>
   </xs:choice>
  </xs:complexType>
 </xs:element>
 
 <xs:element name="c">
  <xs:complexType/>
 </xs:element>
 
 <xs:element name="x" type="unknown1"/>
 <xs:element name="y" type="unknown2"/>
 <xs:element name="z" type="unknown3"/>
</xs:schema>

So yes, you can do incremental development of a schema for a complex
XML language.

ht
-- 
 Henry S. Thompson, HCRC Language Technology Group, University of Edinburgh
                     Half-time member of W3C Team
    2 Buccleuch Place, Edinburgh EH8 9LW, SCOTLAND -- (44) 131 650-4440
            Fax: (44) 131 650-4587, e-mail: ht@inf.ed.ac.uk
                   URL: http://www.ltg.ed.ac.uk/~ht/
[mail really from me _always_ has this .sig -- mail without it is forged spam]