This article records tradition as it has been passed down and reported. Its sources are not yet part of the atlas's verified catalogue.
A trecena entry records a specific, named thirteen day period within the two hundred and sixty day tonalpohualli calendar used across Mesoamerica, identified by the day sign and number that opens it, considered for the documented character, patron or omen the tradition assigned to that period as a whole. Cycles of Time and Meaning in the Mexican Books of Fate reads the surviving painted almanacs specifically for how they organize and interpret the trecenas, treating each one as a documented unit diviners actually consulted rather than an abstract mathematical division.
An entry records a trecena's opening day sign and number, its documented patron deity or governing force where the almanac tradition names one, and the character, favorable, difficult, mixed, the sources attribute to a child or undertaking begun within it.
Where different surviving almanacs assign a trecena somewhat different patrons or omens, an entry records that documented variation across sources honestly rather than presenting a single harmonized reading as the tradition's one settled account.
An entry also records which specific painted almanac or codex an assigned patron or omen is drawn from, since the surviving books of fate are themselves distinct physical documents with their own provenance, and naming the actual source keeps a trecena's recorded meaning checkable rather than presented as an anonymous tradition.