XML Schema:

 
I have the following sample XML. 
<TestScript>
  <Description>My Test Script</Description>
 <FileName>sample.in</FileName>
  <Usage>Usage description</Usage>
  <PreTest>
     .....
  </PreTest>
  <Test> 
     .....
  </Test>
  <PostTest> 
     .....
  </PostTest>
</TestScript>
 
All these element can appear only once. The Description, FileName is
required. Usage is optional. And the PreTest, Test and PostTest sections
are required. The order of the Description, FileName and Usage elements
is not important. that is they are an unordered list of elements. But
they should appear before the PreTest, Test and PostTest element. But
the order of the PreTest, Test and PostTest elements are important and
should be in that order. how do u specify a schema for this. I tried
defining a group with xs:all containing the Description, FileName and
Usage elements. And then for the element TestScript i defined a complex
type which is a sequence of the group and the PreTest, Test and PostTest
elements. Wheni try to validate this, i get the following error: 
 
org.xml.sax.SAXParseException: cos-all-limited.1.2: An 'all' model group
must appear in a particle with {min occurs} = {max occurs} = 1, and that
particle must be part of a pair which constitutes the {content type} of
a complex type definition.

 
Any help on this. I havent defined any min occurs or maxoccurs for the
xs:all element.