17. The computer-readable storage medium of claim 16 , wherein the operations further comprise combining adjacent sets of matching elements into a group of matching elements.
18. The computer-readable storage medium of claim 17 , wherein the operations further comprise: assigning an identifier indicating moved and changed elements to the adjacent sets of matching elements when the adjacent sets of matching elements include two instances of matching elements assigned the identifier indicating moved elements that are separated by an intervening set of matching elements assigned the identifier indicating changed elements.