Editing Old Irish (section)

=== Vowels ===
Written vowels ''a, ai, e, i'' in poststressed syllables (except when absolutely word-final) all seem to represent phonemic {{IPAslink|ə}}. The particular vowel that appears is determined by the quality (broad vs. slender) of the surrounding consonants and has no relation to the etymological vowel quality:
:{|class="wikitable"
! Preceding consonant !! Following consonant !! Spelling !! Example
|-
| broad || broad || {{angbr|a}} || {{lang|sga|díg'''a'''l}} {{IPA|/ˈdʲiːɣəl/}} "vengeance" ([[nominative case|nom.]])
|-
| broad || slender (in open syllable) || {{angbr|a}} ||
|-
| broad || slender (in closed syllable) || {{angbr|ai}} || {{lang|sga|díg'''ai'''l}} {{IPA|/ˈdʲiːɣəlʲ/}} "vengeance" ([[accusative case|acc.]]/[[dative case|dat.]])
|-
| slender || broad || {{angbr|e}} || {{lang|sga|dlig'''e'''d}} {{IPA|/ˈdʲlʲiɣʲəð/}} "law" ([[accusative case|acc.]])
|-
| slender || slender || {{angbr|i}} || {{lang|sga|dlig'''i'''d}} {{IPA|/ˈdʲlʲiɣʲəðʲ/}} "law" ([[genitive case|gen.]])
|}

It seems likely that spelling variations reflected [[allophonic]] variations in the pronunciation of {{IPA|/ə/}}.