Sorry to just barge in, but i did not see a page to introduce myself.
I'm here to learn more about non-european glass, and sofar i allready have seen several names/brands that don't mean a thing to me
I am a little familiar with VSL though, living in Belgium and i can say that the initials 'PU' stand for pièce unique, which translates in unique piece
This doesn't mean that you have got the only one in the world, it is just that it slightly differs from an existing model.
Hope this helps and i am looking forward to learn and participate here.