I'm hoping of you fine people has a script that will tag all the points
on one poly mesh that are inside another poly mesh. I'm also hoping that
you'll share said script...
I blindly tried with UVtoLocation, but I don't really understand how and
what it does.
Is there any sample somewhere on how to plug things ?
It sounds like you've got a location and want to get the U value. In that case, plug the location into the Source of a Get Data node and use it to look up PointU.