 In the Attic dialect of Ancient Greek in the 5th century BC, the first member of each pair is a short closed vowel , and the second member is a long open vowel .In some interpretations of Coptic phonology, it is assumed that the length difference is primary, with ε/η and ο/ω is .Other scholars argue for a different analysis in which ε/η and ο/ω are interpreted as and .