Upsilon: The Coptic Letter (Value 400), from Greek Upsilon

Upsilon is the twenty first letter of the Coptic alphabet and carries the numeral value four hundred. This atlas names it with the Greek name deliberately. Coptic renamed several of the Greek letters, and for this one the authorities do not agree: scholarly grammars of the Sahidic dialect record one Coptic form of the name, alphabet charts in ordinary Coptic Orthodox use commonly print another, and the run that wrote these rows could not establish which had the better claim without asserting something it had not verified. The Greek name is used here as a neutral label and the disagreement is recorded rather than resolved.

Nothing about the letter itself is unclear. It writes the second element of the digraph Coptic uses for the u vowel, following ou, exactly as Greek does, and it appears independently in Greek loanwords. Scribes marked it with two dots above where it had to be read as beginning its own syllable rather than joining the vowel in front of it, a device Coptic also uses on iota and took from Greek manuscript practice. The mark is a reading aid and changes nothing about the sound. In the numeral series upsilon is worth four hundred, and it belongs to the run of hundreds that ro opens.