Ask each musician on a country record what they play on a verse and you get a different answer from every chair, because the true answer depends on the groove. This page fixes that: four named grooves, each broken into a ONE-BAR CELL per chair, played across a three-bar frame — the tonic, the subdominant and the dominant of the key of G — so a chord change actually happens under the part.
THE VOCABULARY is small and declared, not assumed. A number — 1, 3 or 5 — is a bass-note CHORD TONE: which note of the chord currently sounding the bass chair plays, never a chord-of-the-key number (this site does not chart progressions in digits). D and U are a down- or up-strum. chop is a closed, muted percussive chord — the mandolin's chop, and the banjo's vamp. roll is a three-finger roll pattern over the beat: thumb, index and middle picking through the chord one string at a time, a steady stream of single notes instead of one struck chord — one picked note per slot, so a roll through a whole bar is a whole row of them. run is a short fill — a handful of notes, not held. sustain is a held pad tone. A blank slot is a rest, and a rest is as real a part of the arrangement as a note.
Every pitch below is derived, not typed: a bass-note degree over the G-C-D frame is transposition arithmetic from the chord's own root, and scripts/validate-parts.js recomputes it independently on every change, along with which chair rests on every single slot of a groove and whether each groove's table still reads exactly what its data declares.
None of the chairs named here is this site's to teach in depth. Guitar, bass, mandolin, banjo, fiddle, dobro, lap steel, pedal steel and piano each have a deep home elsewhere in the network — the chord shapes, bar positions, pedal moves or voicings, the tunings, the technique — and every reference section under Instruments doors out of here, to that home or to the same page on the network's hub. What this page adds is the layer none of those sisters can write, because it only exists where the chairs meet: which one plays which slot, in which groove, and what that slot actually sounds. A chord chart tells a guitarist what to play; it does not say whether the bass is doubling the root or walking to the fifth two beats later, whether the banjo is rolling through the bar or vamping on the backbeat, or whether the fiddle is holding a pad or resting entirely. That is arrangement knowledge, and it is what a producer or a bandleader actually decides — not which chords, but which chair carries which part of them, bar by bar.