major and minor in one position · a whole octave on three strings
Built as a memo rather than a table: the thing worth hanging it up for reads across the room, with the full reference in smaller type below it.
Three sizes in one archive — from a sheet on the fridge to a poster on the wall.
The filled dot is the root and the figure inside each dot is the degree of the triad. The dots are calculated from standard tuning; the sheet prescribes no left-hand fingering.
Three strings give exactly an octave — 12 semitones, the same as four do. An extra string ought to widen the range, and it does not: on four strings the octave simply falls one note to a string, while on three one string takes two.
The tuning shows why. The third and first strings are 9 semitones apart, so an octave is three short — and those three frets have to be walked up the neck, which is why this shape leans forward instead of back.
Minor here shows a rare case that is plain to the eye on the grid: the third drops a semitone, but on its own string it would land on a fret the position does not contain, so the same note is taken on the neighbouring string. One pitch, another place.
Why the numbers can be trusted. Every countable number here is computed from data rather than typed in, and the sheet must pass 13 independent checks before it is allowed to build — how many items there are, the order they come in, and the claim in the highlighted box itself. If one fails, there is no file.
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