Inscriptions at Piedras Negras are shown to form a pattern of discrete sets of records, each inscribed on a group of consecutive monuments beginning with a stela depicting the “ascension motif.” The earliest date in a series, identified by the upended frog glyph and called an “initial date” precedes the first dedicatory date by a number of years, falling within the span of an earlier series. A date in the first dedicatory hotun of each set is marked by a “toothache glyph” and is called the “inaugural date.” The intervals between these dates are such that no single series exceeds the span of a reasonable lifetime, and it is suggested that the initial date represents something in the nature of a birth or name day of a ruler who accedes to power on the inaugural date, and that each set of monuments records the history of a reign. The representations on monuments are interpreted as portraits of rulers and their families. Initial and inaugural dates at other sites are identified by their respective glyphs, but no articulated series of reigns has been found outside of Piedras Negras.

The variations of the upended frog and toothache glyphs suggest that they are essentially verbal action glyphs. Other action glyphs are correlated with motifs on Yaxchilan lintels, where they follow close upon date notations. Groups of glyphs following the action glyph are identified as appellatives, and are found to contain feminine head prefixes when they refer to robed or skirted figures of women. It is suggested that “ben-ich” katun notations occurring with appellatives of rulers are to be counted from their initial dates. Lunar and determinant meanings ascribed to dates are shown to have no relation to action glyphs accompanying them, and the historical approach is recommended as being more consistent with observed glyphic patterns.