While I don't really like upside down 2 and 3 meaning 10 and 11 (they cause some gymnastic mental transpositions, but not as severe as they do for the upper hal

While I don't really like upside down 2 and 3 meaning 10 and 11 (they cause some gymnastic mental transpositions, but not as severe as they do for the upper half of the fret board, where 15th fret is now the 13th fret, etc) it is still a really cool concept. It makes the octaves on each string visually more clear, but everything else more complex. I get the issue there though - if you treated it like math, using A and B would be way more confusing in this context. There are only so many single-byte characters available.