Cib is the Yucatec name of the sixteenth sign, glossed as wax and as candle, and also read as owl in the later lists. The K'iche' name is Ajmaq, which means something closer to sinner or the one who owes, and highland practice reads the day in terms of ancestral debt and forgiveness, a substantially different sense from the Yucatec one.
Central Mexico gives Cozcacuauhtli, the king vulture, in this position. Vulture, owl and wax candle are three quite distinct images, which makes the sixteenth one of the least stable positions in the shared sequence and a standing puzzle for anyone trying to reconstruct an original list behind the surviving ones.
What the traditions do agree on is the connection with the ancestors and with what is owed to them, whether that is expressed through the vulture that consumes the dead, the owl that announces death, or the candle burned at a shrine. Cib opens a trecena once in each round and is not a Year Bearer in either the Classic set, Ik, Manik, Eb and Kaban, or the Postclassic Yucatec set, Kan, Muluc, Ix and Kawak.
That instability has a practical consequence for anyone comparing lists. A table equating the twenty Maya signs with the twenty Nahua ones position by position is accurate as a statement about order and unreliable as a statement about meaning, and the sixteenth position is where it fails most plainly. The count travelled as a structure; the imagery attached to it was local.