Rịba ama amaokwu a dị n'okpuru ma zaa ajụjụ ahụ mgbe e mesịrị n'otu asụsụ ahụ dị ka amaokwu ahụ:  Nkọwa: Mgbanwe ụda olu kachasị dị iche iche nke na-ekewa Proto-Indo-Iranian site na Proto-Indo-European bụ ọdịda nke ụda olu * e, * o, * a n'ime otu ụda olu, Proto-Indo-Iranian * a (mana lee iwu Brugmann). Iwu Grassmann, iwu Bartholomae, na iwu ụda Ruki bụ ndị zuru oke na Proto-Indo-Iranian.  Ajụjụ: Gịnị bụ ọdịiche kasị pụta ìhè?
ọdịda nke vowels * e, * o, * a n'ime otu vowel