The Nashville number system writes chords as scale degrees — 1, 4, 5, 6m — instead of letter names, so the same chart works in any key without being rewritten.
Songhub recognises Nashville numbers alongside letter chords. Enter 1, 6m, 4, 5, 2m/4 the same way you'd enter C, Am, F, G7, Dm/F, and it renders correctly either way.
Add a flat (b) or sharp (#) before or after the number for accidentals, for example b3, #4, 7b, 5#.
Because numbers describe a chord's position in the key rather than a fixed pitch, a Nashville chart combined with Songhub's transpose directive covers a song moving to whatever key a singer needs on the night.