I still have a gap in my understanding of how atlas's are arranged. My assumption from reading the Therion Book is that the origin and origin-label commands are about how to position the tessellation of atlas pages on the 2D cave image. (Sorry, have not downloaded the latest version just yet) My INDEX.th file contains; centreline cs EPSG:27200 #NZ Map Grid 1949 #Entrance co-ordinates fix N2@n 2500597 6023471 751 #NZMG GL entrance endcentreline and my layout file contains; origin-label 2 A #label type <across> <down> 2 A gives A1, 1 A gives A0, 0 A gives A-1 origin 2500600 6023000 600 meters #co-ords of lower left corner of first atlas page If I leave out the last line I get perfect atlas's (and all other outputs for that matter) - just not a very efficient use of 'paper'. If I include the last line I get; D:\Program Files\Therion\therion.exe: error -- mixing local and global coordinate systems not allowed -- conflict with cs specification at LayoutPlanThisAtlas.thc [11] The origin co-ordinate given is just to the bottom left of the cave in the projections I am using (plan, elevation 290 deg) so that when I have the whole cave system drawn it will fit on a grid of A2 sized pages that is two sheets high (rather than three) I am using rotate 070 to orient the plan nicely on the paper. (I think once I have this sorted out I will be able to use a more sensible origin-label specification) Is my understanding of the purpose of these two commands correct? I have tried a number of spellings of 'meters' and leaving out the units to no avail. Any ideas? Bruce