the initial discourse of a theatrical piece, usually in religious theater
John F. Schwaller discusses Juan Bautista's Confessionario and describes the tlahtolpepechtli as the "fundamentals."
The Byron McAfee collection at UCLA has a typescript Nahuatl version of a huehuetlatolli play with this title (possibly from the Confessionario?), with added corrections in Spanish. He made the copy ca. 1940. See Box 17, Folder 7.