Gb1-21 is an extraordinary glyph without anything similar among all the rongorongo texts, it is unique:

		242
Gb1-21	Gb1-22 (252)		Ga1-22 (495)

I will here attempt to get a grip on it, because it ought to have something to do with rau hei in Gb1-22.

The way to do it is to make a detour to the text of H and the meaning of number 314.