Arcturus hendecatonic notation
Arcturus hendecatonic notation is a notation system for EDTs and no-twos music, developed by CompactStar. It is based on the 2L 9s⟨3/1⟩ MOS scale generated by approximately 5/3. The 5/3 generator connects this scale to the 3.5 subgroup (as well as Arcturus temperament), similar to how the diatonic scale is connected to the 3-limit. The preferred generator for the scale is the patent val 5/3, unless it is outside
The 9|1 mode of 2L 9s⟨3/1⟩ is represented by 11 naturals CDEFGHJKLAB, and #/b accidentals are used to raise and lower by a chroma (L - s). We assume the TAMNAMS convention of zero-based indices for relative notation. Thus, the 13edt (Bohlen-Pierce) gamut is as follows:
| Steps | Absolute notation | Relative notaiton |
|---|---|---|
| 0 | C | perfect 0-step |
| 1 | Db | minor 1-step |
| 2 | D | major 1-step |
| 3 | E | major 2-step |
| 4 | F | major 3-step |
| 5 | G | major 4-step |
| 6 | H | perfect 5-step |
| 7 | J | perfect 6-step |
| 8 | Lb | minor 7-step |
| 9 | L | major 7-step |
| 10 | A | major 8-step |
| 11 | B | major 9-step |
| 12 | C | perfect 10-step |
The chord 3:5:7 is notated as C - H - L (P0 - P5 - M8). To notate larger EDTs such as 28edt, this notation can be combined with ups and downs notation, with ^/v accidentals raising and lowering by 1 EDTstep: