In this paper, we study the Nahua glyphic script as used in the Codex Aubin, a post-Conquest codex produced in 1576 that narrates the traditional Aztec founding myth and chronicles indigenous life in the early colonial period. The text consists of a preconquest-style annal written in the form of a European book; traditional depictions of events and transcriptions in the traditional glyph script are paired with Nahuatl glosses in Roman script, allowing for analysis of glyphs alongside their intended readings. In particular, we look for evidence of phoneticity in glyphs; a number of Spanish language names are transcribed in glyphs in the Codex, providing yet-undescribed examples of phonetic glyph compounds. Further, we also explore the generation of new logograms and phonetic compounds to capture Spanish-language lexemes in the post-Conquest period. We demonstrate the fundamentally polyvalent usage of the script with novel data, interpreting the simultaneous usage of multiple modes of meaning-conveyance and proposing novel readings of some glyphs. Finally, we also investigate the assembly and visual organization of complex glyphs in the codex. In particular, we detail a new modality of glyph usage, which we dub ‘emphatic cross-reference’ — it involves the assignment of extra-graphemic meaning to individual glyphs by means of their visual organization in compounds. To our knowledge, this particular usage of the Aztec script is undescribed to date, and we preliminarily detail our analysis of a few examples found in the Codex Aubin.