using XSL to replace XML nodes with new nodes

Question

I need an XSL solution to replace XML nodes with new nodes.

Say I have the following existing XML structure:

Answer 1

Here is one correct solution, which is probably one of the shortest:

 
 
 

 
  
   
  
 

 
  BBB
  CCC
  DDD 

When this transformation is applied on the provided XML document, the wanted result is produced:

    
        BBB
        CCC
        DDD
    

Do note:

1. The use of the identity template.

2. How the identity template is overriden by a specific template -- only for a criterion element, whose string value is 'AAA'.