Thanks Murray. Very interesting.I'll have a playwith those ideas which i'm sure will improve my tuning (it needs it!). Very well thought out by the look of it But they don't deal with the point I was making, the noticably out of tune octaves you get on most guitars.Basically a B on the A string if perfectly in tune with an open B string will lead to a pair of C's out of tune with each other one fret up.That's nothing to do with equal temperament versus perfect intervals, it's about string distortion fretting near the nut. And maybe this guy's patent system helps deal with this?