Two possible workflows for drawing map over xvi: First: 1) integrate new centerline in whole cave (loops closed) 2) process whole cave and export xvi 3) draw over xvi 2) process map Second: 1) process only new centerline and export xvi (no loops) 2) draw over xvi 3) integrate new centerline in whole cave (loops closed) 4) process map _______________________________ I don't think there is any significant difference in the result. When I first started out with Therion I used the 2nd approach. After a while our dataset grew and I became more comfortable with the data organisation we had stumbled upon, and the way we were working, the 1st approach meant a smoother workflow and less steps/chances for error. We still use the first approach, but now that we generally use PocketTopo (and have not yet dared to use the 'close loops' feature - sorry Beat) I think that the xvi created by the pockettopo export/therion import process is effectively giving us an xvi that is not distorted by the integration into the overall cave. Even when the survey centreline is already integrated and distorted. I guess as others have said, therion treats the survey centreline and drawings completely independently. So, I could be wrong, but I think that you can do it any way that suits the workflow/ organisation of your dataset. Bruce