There is a central sign in Pax which returns in Vayeb:

16 Pax	17 Kayab	18 Cumhu	19 Vayeb
301-320	321-340	341-360	361-365

The sign (tun) has been compared with a wooden drum:

"The tun glyph was identified as a wooden drum by Brinton (1895, p. 92), and Marshal H. Saville immediately accepted it. Figure 49 [excerpt above] shows the Aztec drum representation relied on by Brinton to demonstrate his point. It was not then known that an ancestral Mayan word for drum was *tun: Yucatec tunkul 'divine drum' (?); Quiche tun 'hollow log drum'; Chorti tun 'hollow log drum' (Wisdom 1940, pp. 175-176)." (Kelley)

A drum was anciently the means by which to communicate with the gods above, the shaman's instrument. At the end of years drums are useful.

We can restructure the Mayan month calendar to make it more comparable with the calendar of the year in G:

First we should notice the open top in 5 Tzek, the first of 10 sun months, which surely must mean that sun is arriving, because also 16 Pax has this type of open top (to let the sun escape):

5 Tzek	16 Pax

The sign at top left in Tzek is reversed compared with the similar sign in Pax. The Mayan glyphs have the future at left and the past at right. It means that in Tzek the future sign points upwards, while in Pax it points downwards.

There are 4 months of spring and then comes the rain. 4 * 20 = 80 days for spring can be compared with 4 months counted by a measure between 28.5 to 31 (i.e. equal to 114 - 124 days) according to the G calendar:

5 Tzek	6 Xul	7 Yaxkin	8 Mol
9 Ch'en	10 Yax	11 Sac	12 Ceh

Regarded so, Mac and Kankin become special:

80
	5 Tzek	6 Xul	7 Yaxkin	8 Mol
80
	9 Ch'en	10 Yax	11 Sac	12 Ceh
40			2 * 80 + 40 = 200
	13 Mac	14 Kankin
80
	15 Moan	16 Pax	17 Kayab	18 Cumhu
5		2 * 80 + 5 = 165
	19 Vayeb
80
	1 Pop	2 Uo	3 Zip	4 Zotz

Kankin looks like the month when sun is reaching the horizon in the west. The following Moan shows darkness has fallen. Half a year is 180 (because Vayeb has 5) and 180 = 9 * 20. From Tzek up to and including Mac covers 180 days.

Counting from Pop we have 4 * 20 + 180 = 260 days including Mac. In Kankin sun dies. His spirit will then rise 40 days later, when there are 60 days left of the year. 360 - 60 = 300. Pax is the Mayan equivalent of Hua Reva:

60
	Gb3-7	Gb3-8	Gb3-9 (300)	Gb3-10	Gb3-11

"The [tun] glyph is nearly the same as that for the month Pax (T549), except that the top part of the latter is split or divided by two curving lines. Brinton, without referring to the Pax glyph, identified the tun glyph as the drum called in Yucatec pax che (pax 'musical instrument'; che < *te 'wooden). Yucatec pax means 'broken, disappeared', and Quiche paxih means, among other things, 'split, divide, break, separate'. It would seem that the dividing lines on the Pax glyph may have been used as a semantic/phonetic determinative indicating that the drum should be read pax, not tun (cf. de Gruyter 1946, p. 27). Thus, one may expect that this glyph was used elsewhere meaning 'to break' and possibly for 'medicine' (Yuc. pax, Tzel., Tzo. pox)." (Kelley)