As briefly mentioned in another email, we are surveying a cave with a total station, due to the amount of metal, making compasses useless. The total station gives its readings in degrees:minutes:seconds, which is fine for therion, but not so good for PocketTopo (or it might be my ignorance.) The problem encountered is it works on the units of zero as horizontal and works mathematically, so -10 in caver speak is 350 in total station. When this it put into therion (and by association I assume survex) you get an out of range error. gradient reading out of range -- 359 Okay I have solved this by converting all the down ones, but it would be good if Therion could use this convention. maybe generally giving a warning that can be suppressed for individual centrelines as a real icing feature? Andrew