I have an Istanbul Mehmet prototype cymbal that has no logos or stamps and just some notes scrawled on the back in marker. It's not like anything in their product line that I see. I'm confident in the lineage since I got it from a reliable source. But when I was googling "prototype" cymbals I found a bunch especially by Sabian and Zildjian that are called prototypes but they seem to be part of complete lines with multiples available of each model complete with logos. Is there something in the cymbal industry where there's a broader definition of prototype?