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 resonator player reads a number as a place to stop the bar — the strings are already a chord, so what the digit changes is not the grip but where along the neck the bar has to be sitting when the bar of music starts. The open strings already spell a chord, so a number is answered with a position rather than a grip, and the whole reading job is arriving at the right one square on the beat.