D as a Nashville Chart Sees It

Count off in D and the seven numbers name D, E, F#, G, A, B, C# — in that order, every time, on a page that never mentions D 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 lap steel player reads a number as a fret to slide to, with an open tuning underneath that already spells one chord — so the chart is read as a series of distances from wherever the bar happens to be. There is nothing to finger and no grip to form — the diagram is one straight bar across a fret, so the digit resolves to a single place to be, and everything expressive happens on the way there.