In studies concerning the manuscript tradition of medieval Galician-Portuguese lyric poetry, the treatment of words beginning with h usually depends on etymological considerations. Accordingly, critical editors are more likely to spare the first letter of home and ha (Lat. hominem, habet) than that of hir and h?a (Lat. ire, unam). As this study shows, in the songbooks B and V and in the Sharrer parchment, etymology seems to play a secondary role at best, as initial h occurs almost exclusively in five lexemes: the noun home, the verb hir, the article h?u/h?a and the adverbs hi and hu (Lat. ibi, ubi), which all drop their aitches when preceded by words with final vowel elision (e.g. "algun home" vs. "tod' ome", "quisera hir" vs. "quisera-m' ir", etc.). This h /Ø alternation, characteristical of the 13th-14th century Portuguese (but not Galician) tradition, is the counterpart of the analogous treatment of h in medieval French, Occitan and Italian. It constitutes an element of what might be defined the ortografia dionisina, distinct from the ortografía alfonsí of the Cancioneiro da Ajuda, the Vindel parchment and the MSS of the Cantigas de Santa María.