F as a Nashville Chart Sees It

Count off in F and the seven numbers name F, G, A, A#, C, D, E — in that order, every time, on a page that never mentions F anywhere.

Three of those need a mark and four do not. A bare number is a MAJOR chord, so 2-, 3-, 6-, 7- are what a chart writes when it wants the chord the key would have supplied anyway; a bare 2 means the writer wanted something else and meant it.

A banjo player reads a number as somewhere to be when the roll comes back around — the right hand keeps going through the bar line, so a chart change is a destination the left hand has to reach without the pattern stopping. The picking hand is committed a beat before the change, so the digit has to be converted while the previous one is still sounding.