LucyTuning is derived from pi and the writings of John 'Longitude' Harrison. This system enables users to modulate, transpose and emulate any tuning system that they can imagine. The mapping/navigation system conforms to traditional musical harmonic and note naming conventions and concepts.

The first practical LucyTuned guitar was the Mk V, which was first made in 1986. It has twenty-five frets per octave.

The story of its design and construction can be found in chapter one of Pitch, Pi, and Other Musical Paradoxes . This is the design used by Arc-Angel and there are now a few hundred copies which have been made in all parts of the world. Although the design was patented, permission has been given for their non-commercial production for personal use. The design details have been evolving, and it is now proposed that new users start with the nineteen fret per octave model, and with experience add twelve further frets to make it thirty-one frets per octave.

http://www.harmonics.com/lucy/lsd/frets.html

More on Tuning: http://www.guitarsite.com/tuning.htm