Coptic renamed several of the Greek letters, and this atlas uses the Coptic names where they are settled: ei for epsilon, laula for lambda, ou for omicron, semma for sigma. For upsilon the authorities disagree. Scholarly grammars of the Sahidic dialect record one Coptic form, alphabet charts in ordinary Coptic Orthodox use commonly print another, and the run that seeded these rows could not establish which had the better claim without asserting something it had not checked. The Greek name is used in the meantime as a neutral label.
What would resolve this A survey of the letter names given in the principal Coptic grammars alongside the names taught in Coptic Orthodox church schools in Egypt and the diaspora, distinguishing the scholarly Sahidic tradition from living Bohairic practice, and saying which name belongs to which tradition rather than choosing one for both.
OpenCoptology; Coptic Orthodox liturgical practiceDivinity Atlas Open Questions Register, First Edition