Muluc is the Yucatec form; the K'iche' daykeepers call the ninth day Toj, a word meaning payment or offering, and that reading of the day as the settling of a debt is the one that carries most weight in living highland practice. The Yucatec name is glossed as water and as jade, and the Classic glyph is read as a water sign.
Central Mexico places Atl, water, in ninth position, matching the Yucatec gloss precisely. The difference between Yucatec water and K'iche' payment is not a contradiction so much as two aspects of the same idea, since offerings in Maya practice are frequently poured.
Muluc is a Year Bearer in the Postclassic Yucatec system Diego de Landa recorded, where the four permitted openers of a Haab year are Kan, Muluc, Ix and Kawak. It is not one of the Classic four, Ik, Manik, Eb and Kaban, nor of the set the highland communities use today. The two systems are separated by five positions in the twenty, and the shift between them is one of the standing problems of Maya calendrics, discussed in terms of a change in the convention for naming the first day of the year rather than a change to the count itself, which ran without interruption.
The reading of Toj as payment sits at the centre of highland ceremonial life, where offerings are described as the settling of what is owed to the ancestors and to the earth. That vocabulary of debt runs through Maya religious language far beyond the calendar, and the ninth day is where the calendar and that vocabulary meet most directly. The atlas records the association and leaves its use to those trained in it.