I also do as Xavier describes, and agree that compass bearing (even if clino is vertical) seems to be the logical way to orient LRUD. Bruce -----Original Message----- I completely agree with you that NSEW is not not a good way to measure the shape of about-vertical passages. In fact I personally never measure dimensions in NSEW directions but in the direction of the shot (or of the preceeding shot if it is absolutely vertical), in the reverse direction, on its right and on its left. I use LRUD with Up meaning in the (horizontal direction of the shot and Down the opposite. As we have to give a bearing anyway for vertical shots, why not use it to orient the dimensions instead of a vthreshold-offset that should be changed for each new shot? Xavier