F# Dim on Bass, and the Number That Writes It

F# Dim spells F# – A – C. That much is fixed. What is not fixed is what it is CALLED: hand the same chord to a chart in A and it is written 6; hand it to a chart in B and the identical chord is written 5, on a page nobody had to rewrite.

F# answers to the 1, 2, 3, 4, 5, 6 and the 7 depending on what got called: it is a plain number in 7 of the twelve keys and needs an accidental in the other 5.

A bass player reads a root per number, and the slash marks that override it — the only player on the floor for whom a 1/3 is an instruction rather than a colour. Most of what is written above the number never reaches down here; what does reach is the root, and whatever a slash mark says to put underneath it instead.

Every shape below is drawn for EADG, 4 strings, open shapes first and movable ones after them, and each one plays back — because the fastest way to check that a number was read right is to hear it.