I learned over this week that SBMAX pre-sort uses the LNW in the RAW file, and if none is present it assumes the survey line goes straight from Point A to Point B. This wreaked a bit of havoc on a customer who did a river survey (not at all a straight line) and he tried to run pre-sort without an LNW and it was a mess.
I managed to "force" an LNW into the files using an XYZ produced from the raw data, then using XYZ->LNW, then copying it into the header of the raw data files (using a little bit of Python magic). It would be a nice feature if SBMAX could have an option for doing this so if a customer didn't use an LNW they could still get a meaningful result from pre-sort.