How to use attribute values from another XML file as an element value selection in the current XML

Question

I have two XML files. One is the main XML file and the other one is used as a lookup table. Here is the main XML:

Answer 1

This is the way I would do it (although I like Martin's use of xsl:key):

I modified main.xml and lookup.xml to show the dynamic name lookup.

main.xml

  
    test1
    test2
    test3
    testing new element
  
  
    test4
    test5
    test6
    testing new element again
  

lookup.xml

  fieldA
  fieldB
  fieldC
  fieldD

XSLT 1.0 stylesheet

output

  
      test1
      test2
      test3
      testing new element
  
  
      test4
      test5
      test6
      testing new element again