2. I have chosen not to colour the strange quartet Gb6-21--24, because they seem to be outside the main flow of the glyphs:

end of old 'year' (?)
Gb6-17 (400)	Gb6-18	Gb6-19	Gb6-20

beginning of new 'year' (?)
Gb6-21	Gb6-22	Gb6-23	Gb6-24

Gb6-25	Gb6-26 (409)	Gb6-27	Gb6-28

They probably stand at the beginning of the new 'year', before Rogo (in Gb6-26) arrives. Their positions are therefore analogous to those glyphs which precede vaha mea at the beginning of the front side:

beginning of new 'year' (?)
Gb8-30 (1)	Ga1-1	Ga1-2	Ga1-3	Ga1-4 (5)

In the dark preceding the arrival of the light from the newborn Sun there are no colours.

The glyph type in Gb6-21--24 is rare in the rongorongo texts. Its curved outline can be contrasted with that of the straight henua. It is possible to can count to 2 + 2 = 4 henua signs in Ga1-1--3 (the pointed 'arms' is another kind of sign).

It is probably significant to find this rare kind of 'beast' in Monday: