Monarch
Monarch is a rank-3 straddle temperament tempering out 81/80[-3] and 64/63[+3] in the 2.-3.+3.5.7 subgroup. The name comes from the combination of Meantone and Archy, the two linearly independent combined to make Monarch. Extensions and specific erac tunings make use of combining the two tunings of 3. The name implies that this is a temperament of greater scope or importance. It may also be called Archtone, making the same use of the "arch" affix.
Optimization
There are multiple ways to optimize Archtone. The Meantone diatonic major third 81/64[-3] is broadly a sharp 5/4, which has several benefits when used in Archy pental blackdye according to the above standards. It refines aberrismic melodic properties, preserves the tuning of 7/5, and happens to coincide with a +1+1 major triad. The diatonic minor third cannot be tuned to 6/5 or sharper without an excessively flat fifth.
On the other hand, the narrower capture zone of 9/7 and multiple non-2 primes in its factorization imply that it should be tuned more accurately. This may be done in two main ways for Meantone septal diasem: In 110edo, 9/7 is 81/64[+3], a straightforward Archy diatonic major third. In 86edo, 7/6 is tuned more accurately with 32/27[+3] due to the sharper 3. 9/7 is obtained by 3/2[-3] / (32/27[+3]), subtracting the Archy minor third from the Meantone fifth. This sacrifices 9/7 to improve sharp 7 and flat 11.
