I just checked on my little experiment of some years ago, and I misrepresented it.
PocketTopo automatically detects backsights if they are taken immediately after a foresight. So the software handles the station naming, no user intervention required. That much is true. You end up with something like: 1.4 splays 1.4 1.5 shot 1.4 1.5 shot 1.4 1.5 shot
1.5 1.4 shot # for back shots it will recognise 1 or more shots within tolerance as 'back legs', so you can do as many as you want, I think 1.5 1.4 shot 1.5 1.4 shot 1.5 splays 1.5 1.6 shot etc
While I processed the only survey I ever did this way with Therion... Not true. I did not bother parsing the data from PocketTopo, as the passage ends were too far apart to consider digging, and so no point to mapping with Therion (we already have an older map).
Never the less, I am almost curious to see what TopParser and Therion does with it. Lots of loops and doubled survey length I expect. Maybe I will process it one day. Tarquin You mention that SexyTopo deals with this by treating the backsight as a splay. Does it detect and label this splay as a backleg if it is within tolerance for the previous leg? I think it should (similarly to PocketTopo). While I don't tend to use backsights as a rule, there is that 1 in 100 occasion where I do consider it, and I expect that the field software should automatically detect this and number the shot/leg accordingly. In a generic sense, rigorous foresight/<move to next station>/backsight/splay is a valid survey protocol (along with variations of that). Bruce