That would make sense. More likely that it is particular users accidentally draw near the edges of the screen when zoomed out. That would explain why some cave survey bookers have this more often! In the example I sent, the stray lines are near the end I expect, lines 504 to 506. Have not tried it yet in middle of something else if I delete those three lines, the XVIGRID extent will still be very large. Where can I find the syntax description so that I can intelligently edit it? There are 8 numbers in a row. Bruce _____ From: therion-bounces@speleo.sk [mailto:therion-bounces@speleo.sk] On Behalf Of Martin Sluka Sent: Saturday, 5 October 2013 7:18 p.m. To: List for Therion users Subject: Re: [Therion] drawing files with unnecessary large extents created by therion/topparser Bruce, this is typical for PocketTopo and lines created by mistake, if one didn't switched pen to moving mode before transport of PDA and PocketTopo created a "missed" line somewhere in border of drawing area. It could be just one very short and practically invisible line. Try open the xvi file by plain text editor and find such a lose line. m. Oct 5, 2013 v 5:29 AM, Bruce <bruce@tomo.co.nz>: There is something about the drawing extents that is not right. Not sure if it is just a gap in my Xtherion knowledge, or if there is something unusual about how TopParser (and sometimes the therion convert) creates the files. Can I fix it by manually changing something after the file is created? Most times this does not happen with Therions converter. Martin Sluka - Studio Sluka prodej Hahnemühle DFA tisk fotografií a reprodukcí Na Rovnosti 2692/21 130 00 Praha 3 tel.: +420 603513640 mail: martinsluka@mac.com web: http://www.piezografie.cz