Thanks guys. Yes, I am doing as Footleg suspected and importing already generated survex.3d files in this case. That's partially to save time, as I seem to be on a deadline with this, strange feeling for a survey project, and that's the way much of the data is getting to me. I have also been given some data in Compass.dat files & I can import that into Survex to generate a .3d but I've been never been able to get it to import directly into Therion. Does it?
I could convert the data to Therion but that's time consuming to get right & as I said, I seem to have a deadline on this. However, thanks to Footleg I now know which version of Survex to use. I'd gone all the way back to 1.1.15 just to make sure it worked! Graham
