Ted, In re-reading your post I failed to see the word "XP" and so in theory you should have more "drift" than with RTK. I was assuming RTK which would give you good repeatability with "all things being equal next year...". All GPS has drift but RTK which you know has the least of any (approx 1 inch) within a certain distance from the base. Sorry I read your post to quickly. Any XP drift that may happen to you should be in a parallel fashion to the line created from the two points. Arnie | 
Reuse A-B lines or start over?
