On the facebook "22-Tone workgroup", Cryptic Ruse mentioned that he was working on a non-JI-based general notation system for EDOs 72 and below, based on accidentals for fractions of the Pythagorean apotome (7 fifths, octave-reduced) and Pythagorean limma (5 fourths, octave-reduced), and asked what Sagittal accidentals would be most suitable for 1/4-apotome, 1/2-limma and 1/4-limma. The Sagittal apotome symbol is of course

(or

) and the medium-precision 1/2-apotome is

. My choice for a 1/4-apotome symbol is the 7-comma symbol

because the exact relationship

+

=

is highly suggestive of

+

=

although this is only approximate in standard Sagittal.

With pure fifths, the difference between the apotome (116.7 c) and the limma (90.2 c) is the Pythagorean comma or 3-comma (23.5 c). This is symbolised exactly as

in Sagittal, so the limma is exactly

. But we wouldn't use diacritics for EDOs of this size. We'd just use

for the limma. The 1/4-limma (22.6 c) happens to be between the 5-comma and the 3-comma in size, so we'd use the 5-comma symbol

for the 1/4-limma, and the double-5-comma symbol

for the 1/2-limma.

Summary
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apotome limma
full sharp paosharp
half pakai or vai phai or fai
quarter tai pai