I'm making good progress now on learning how to generate various output from Therion, and have started on generating KML plan maps for google earth. My problem is that my survey data is coming from survex .3d files which I am importing. I am working with data for many hundreds of caves, and they are all fixed using UTM with the European 1979 Datum because that is the coordinate system of the expedition area maps we have had for the past few decades. As far as I can tell, this datum is not included in Therion at the moment. I've checked the epsg file in the source. I specifically need the UTM30N zone as all our caves using this coordinate system are in that zone. Is this something which can be added please? Footleg