Ga2-21:

Here the first (top left) 'arm' (henua) is 'measured', i.e. this period has reached its end. The three remaining periods are still open, because they are in the future.

Henua might be understood as season, the events 'ordered' by the sun and executed through the king. Four such seasons constitute the 'earth', i.e. the year.

The two at the top in Ga2-21 represent the first half-year ('summer') and the left at top the first quarter, from winter solstice to spring equinox.

Ga7-6:

The first half-year ('summer') is 'measured', not yet the second ('winter'). The last of the measured quarters has a vertical cut-off mark, earlier measured ones a perpendicular mark, the 'wound' has 'healed'.

Here the writer has concentrated not on the quarters but on the main structure: the two half-years. Autumn equinox has (presumably) already passed, but that is not noted in the glyph, because then the text misleadingly would tell us about the last quarter of the year (while the subject is the second half-year).

South of the equator east (the future) is at right and west (the past) is at left, as determined by the path of the sun. We are looking northwards and sun will pass zenith there at noon. Southwards there is darkness (winter, night).