Sawmill is the smallest retune on this page and the largest change in character. One string moves and the open strings stop spelling a major chord: what you get instead is a set that refuses to commit, which is exactly what a modal tune wants. It answers to three names — sawmill, mountain minor, and G modal — and the derived table below shows why all three fit.
The retune, string by string
Derived from pitch arithmetic against standard gDGBD — every octave here is computed as the shortest move that produces the named letter, not looked up:
| String | Standard | Sawmill | Semitones |
|---|---|---|---|
| 5 (drone) | G4 | G4 | stays |
| 4 | D3 | D3 | stays |
| 3 | G3 | G3 | stays |
| 2 | B3 | C4 | up 1 |
| 1 | D4 | D4 | stays |
gDGCD — 1 string moves (2).
What the open strings spell
The distinct letters sounding are D, G, C, which reads as Csus2 or Gsus4. Standard tuning, for comparison, spells G major. Which of those readings is the tonic is a fact about the tune you are playing, not about the strings — so this page names every reading that fits rather than picking one and calling it the answer.
What survives
The standard chord library does NOT apply here — a neck string moved, so every fret in it is off by that string's delta. Concretely: string 2 moves up 1, so anything you fretted there is now 1 fret lower. That is not a reason to avoid the tuning; it is a reason to learn it as its own instrument rather than as a transposition of the one you know.
Get there with the tuner, check the open strings against each other by ear, and then use the fretboard explorer on the standard neck to see how far the map has moved. The capo pages cover the other way to change key — the one that leaves every shape where it was.