Sek appears in Diego de Landa's sixteenth-century account under the spelling Tzec, and it is the month his description associates with the ceremonies of beekeepers, held to secure a good yield of honey. Honey and the fermented drink made from it had a settled place in Yucatec ritual, so the association is of a piece with what the colonial sources say about the month elsewhere.
Landa's Relacion is the single richest source for the Postclassic Yucatec calendar and also the most awkward, since he wrote as a churchman describing practices he was working to suppress, and the surviving text is an abridgement of a lost original. Where the atlas reports his festival notices it reports them as his account rather than as the practice of the Classic period, which is separated from him by six centuries and known from different evidence.
A Maya date does not name a month and a number in the way a European one does. It names a day in the 260-day Tzolk'in, by number and sign, and a position in the 365-day Haab, by day and month, and the two together form the Calendar Round, which repeats only after 18,980 days, a little under fifty-two years. Within the Haab the days of a month are numbered from zero to nineteen, and the zero day is not called first but seated, the seating of the month, a usage the Classic inscriptions write with its own glyph.