About the tenor viol

Tuned G C F A D G (low to high): fourths with a major third between strings 3 and 4 (F–A). It sits a fourth above the bass viol (D G C E A D). The tenor is non-transposing. Typically 7 gut frets, tied on and movable; they are a semitone apart, so the names here are the equal-tempered ones (real viols often use meantone).

Clefs: the tenor viol usually reads alto clef (C clef on the middle line, which is middle C). Some editions use tenor clef (C on the 4th line) or octave treble, and high parts can be in treble at pitch. Landmarks: middle line = C4; top line = G4 (open 1st string); bottom line = F3 (open 4th string).

Tuned in E: some tenor viols are tuned E A D F♯ B E, a minor third lower (the same notes as a guitar, with its G string at F♯). Under Settings, choose either notes where they sound (the neck shows the real notes of your viol) or with G fingering: you finger as on a viol in G, the tenor part is written a minor third higher (like a part for a clarinet in A), and it all sounds in tune with the app and the other parts.

Frets: treble, tenor and bass viols all have seven frets of gut tied round the neck; the seventh is a fifth above the open string. Higher notes are stopped on the bare fingerboard above the frets (Settings: Frets 0 to 8 ... 12 shows those places).

Treble and bass viols: the treble viol is tuned D3 G3 C4 E4 A4 D5 and reads treble clef. The bass viol is tuned D2 G2 C3 E3 A3 D4 and reads bass clef, with alto clef for high passages. Their necks can be shown under Settings. When a score plays, the part chosen under Neck shows (in the toolbar) lights up on the neck of its viol; choose Every part to get a neck for each part. Each viol has its colour wherever its parts appear: treble yellow, tenor gold, bass purple.

Sources: VdGSA viol help sheet, Saraband: Viola & Tenor Viol, Writing for viol and voices.