Re: [xml-dev] Help creating DTD

Schematron is another schema language. It lets you take your 
natural language statements and wrap them with XPath-based
tests.  

Here is the description:
 <ORDER> can contain any number of child elements
 <UID> must be included
 <DEALER> must be included
 <ORDERS> must be included

<ORDERS> can contain multiple ITEM(s) but restricted to just ITEM nodes
<ITEM> must have unique id property and the value of item must be numeric > 0

Here is a Schematron schema for those:

<schema xmlns="http://www.ascc.net/xml/schematron">
 <title>Example Schema</title>
 <pattern name="Contents">

  <rule context="ORDER">
   <assert test="true()" >ORDER can contain any number of child elements</assert>
   <assert test="UID" >UID must be included</assert>
   <assert test="DEALER" >DEALER must be included</assert>
   <assert test="ORDERS" >ORDERS must be included</assert>
  </rule>

  <rule context="ORDERS">
   <assert test="count(*) = count(ITEM)"
       >ORDERS can contain multiple ITEM(s) but restricted to just ITEM nodes
   </assert>
  </rule>

  <rule context="ITEM">
   <assert test="count(//ITEM[@id=current()/@id]) = 1" >
       ITEM must have unique id property</assert>
   <assert test="./number() &gt; 0 ">
       The value of ITEM must be numeric > 0</assert>
  </rule>

 </pattern>
</schema>

Cheers
Rick Jelliffe