I had an initial glitch because I tried to create my libraries in an external runtime and hadn't spotted that it uses the main runtime by default. Both scripts seem to have done their jobs, anyway, so thanks once again.

If I foresee using this often, which is a possibility, I may merge the pose and camera scripts into one. On the other hand, there may be situations where I might want to save one aspect and not the other. I was going to procrastinate, but I couldn't decide when to start. :)