If you’re working in publishing, there’s two things that are almost certain. One, you’re working with some form of structured document containing XML (with or without your knowledge). Two, your publication will change constantly throughout its lifecycle. Chances are your published document will have a past and a future, filled with additions, deletions, added value and outdated jargon. Finding what has changed is a start, but means little when those changes contain irrelevant data, are hard to read and even harder to process because of tools not understanding XML.
More control over how change is represented speeds up and enhances your publishing process, especially when you can adapt the output of changes for different reviewers, editors or even customers.