I just initiated a discussion with one of the companies I license one of my products to.  Apparently they have been making my product with various modifications but keeping the overall design of it.  The patent on the product has not issued, but even if it had, the modifications they have made would not mean they have infringed. 

HOWEVER - I spoke with a copyright attorney and was advised that the design engineer drawings that I gave them to make my product are considered mine under copyright law.  As a result, even though the modifications to the inside prohibited me from payment on my patent rights, it is enforceable under copyright law! 

That's right, I am going to get paid on the design now...and I DID not register the copyrights.  Imagine that!

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