Ysi Earth world map II

[Karro]

Well... I may have come up with another possibility: purely additive, with numbers arranged by order, largest to the left, smallest to the right. The base is 6, with special characters representing the 1 through 6 as well as low-multiples of 6 (12 & 18, in particular), powers of six, and powers of six times each of 12 and/or 18 (so special character for 36 = 6^2, 72 = 12 * 6^1, 432 = 12 * 6^2, etc. etc.)

Some possible examples:

15 = (12)+(3) [cardioid plus S-shape]
21 = (18 )+(3) [e-shape plus S-shape]
615 = (432)+(180)+(3) [double-y plus northpole plus S-shape]
468 = (432)+(36) [double-y plus sideways-lasso]
412 = (216)+(180)+(12)+(4) [Sigma-shape plus northpole plus cardioid plus curly-3]

However, so far this doesn't line up with the 989 or 78 figures, or I can't see how it can, yet...

Edit: There's no logical proof of this, as yet. I just wanted to see what would happen if I assumed it was additive, and started plugging in numbers that I knew based on this, and still assuming the north pole is 180. Some other results of this: if the third meridian from the right of our "prime" (unmarked) meridian is 45 (sideways-lasso plus n-shape plus S-shape), then n-shape is 6. Then if the last meridian on the northern continent is 60 (sideways-lasso plus Z-shape), then Z-shape is 24, which is 6*2*2... So it might be the case that we also have a special symbol for each multiple of 6 where the other factor is less than 6, i.e. 6*3, 6*4, 6*5... so we'd postulate a unique character representing 30 as well. That would be the curly-M back a few meridians.