19. A code-portion-handling tool as claimed in claim 17 , wherein said at least one processor is operable to verify such manipulation against said implementation, and to disallow manipulation that is incompliant with at least one of the second data structure and the implementation rules.
17. A code-portion-handling tool as claimed in claim 12 , wherein the at least one processor is operable to manipulate said candidate code portion in dependence upon said implementation.