The boundaries are at fifth errors of +-7.5 cents. Superpythagoreans and Meantones are just on the blue side of these boundaries. I suggest that if you want a fractional-3-limit notation for any of the EDOs in the blue area (a non-standard notation for them), they should be notated as apotome-fractions. i.e. You can imagine the amber underlaying the blue, like sand under water. But the red is fire, and stops at the water's edge.
Many thanks to Cryptic Ruse for promoting fractional-3-limit notations for EDOs below 72, and for showing that it is possible to do it with a small number of accidental symbols.
Here's my proposed mixed-Sagittal symbol set for fractional-3-limit notations (originally posted here: ). I've only shown the upward symbols, but of course there are matching downward symbols too.
I note that all of these symbols contain a left-scroll (to indicate that this is a fractional-3-limit notation and not a JI-based notation), and most of them are Spartan symbols with a left-scroll added. The left-scroll adds an "r" or "l" to the symbol's name.
Notice how the width of the Sagittals increases steadily with the size of their alteration.