Thanks John fir replying. Indeed it seems I am struggling with even basic things, although to reassure you I have had the Primer open on my screen for the last 3 days and tried to watch videos also. I am not new to programming and working with lists of lists etc, but indeed virgin to graphical programming… So, sorry to ask these dummy questions, and I know indeed the feeling of readers as I have been often on their side in other circonstances.
So I need to create some points (4 for a first test) in relative planes (about hundred of them around a volume), with well defined position (u, v) fixed or calculated) in each of these relative planes, but I don’t find how to make a list of them to input the curve-on-a-surface widget. I don’t see how to use “merge” to combine real numbers in 4 pairs, and even how to crete the pairs uv (although I tried the evaluation-expression widget). Maybe I need to use the #C evalaution widget, but that would sound an overkill, or I am tryng something not possible (at least this way) in GH?
I did a #C script to generate a list of UV corrdinate lists but Curv on Surf was still not happy… until I realised that what is called uv is in fact a POINT (or vector) u,v,0. Bluddy confusing label! So then of course the issue was solved and indeed I could use Merge to put my 4 points in a list
https://www.cs.cmu.edu/afs/cs/academic/class/15394h-f18/lectures/gh3/gh3.html : First statement = “A point is not a list (of numbers): it’s a Point object.”