Pointer to Arbortext change tracking markup

See  http://www.arbortext.com/namespace/atict/change-tracking-markup-spec.htm  l for a publicly available writeup of Arbortext change tracking markup.  It was written by a developer for developers, so it isn't an easy read, but it might give some idea of the kinds of things one would need to consider.  After reflecting on the SC conversation today, I'd like to make some general suggestions.  Change tracking is a hugely complex area, and  if we are to make any useful progress, we need to avoid trying to solve problems that should be outside our scope.  The first two things we need to do is forget about how to determine  what the changes are and forget about how to display the changes.
The only thing we can do usefully is make suggestions on how to  mark up the changes in an interchangeable way--leave the "front end"  (change determination) and "back end" (display) issues out of our  discussion, or we'll never make any progress.  That leaves us with the following issues to address:  a.  how to indicate location of changes  b.  how to indicate text/content of changes  c.  how to provide other info about the change including who, when,
version level, etc. metadata as well as what kind of change
(addition, deletion, move)  That will be plenty to tackle for us.  Even that much will be very involved.
paul