I suspect that this glyph should be repeated at 3-b-9 and 11-b-9, for the following reason.
In Maya means "ladder," but the glyph is supposed to represent "an old man."
The next question is, How is this glyph in the sixth place formed?
The month glyph, therefore, should follow in the upper half of 13.
An error of this kind is difficult to detect, because there is no indication in the text as to which glyph is the one at fault.
The head and feet of the lizard, as has been noted, may also be shown by a glyph.
The glyph itself is on the left and the coefficient, here expressed by a head variant, is on the right.
Examples of glyph elision, showing elimination of all parts except essential element (here, the crossed bands).
The glyph belonging to this deity also shows the Chicchan sign as its distinguishing mark.
Again, the phonetic value tun is expressed by the glyph in g, and the sound ca (c hard) by the sign h.
1727, "ornamental groove in architecture," from French glyphe (1701), from Greek glyphe "a carving," from glyphein "to hollow out, cut out with a knife, engrave, carve," from PIE root *gleubh- "to cut, slice" (cf. Latin glubere "to peel, shell, strip," Old English cleofan "to cleave"). Meaning "sculpted mark or symbol" (as in hieroglyph) is from 1825.