Unlike Greek, the Slavic languages had only a single /o/ sound, so Omega was little used compared to the letter O (О о), descended from the Greek letter Omicron. In the older ustav writing Omega was used mainly for its numeric value of 800, and rarely appeared even in Greek words. In later semi-ustav manuscripts it was used for decorative purposes, along with the broad version (Ꙍ ꙍ) as well as the Broad On (Ѻ ѻ).
Modern Church Slavonic has developed strict rules for the use of these letterforms.
Another variation of o is the ornate or beautiful omega, used as an interjection, “O!”. It is represented in Unicode 5.1 by the misnamed character omega with titlo (Ѽ ѽ).
|Unicode name||CYRILLIC CAPITAL LETTER OMEGA||CYRILLIC SMALL LETTER OMEGA||CYRILLIC CAPITAL LETTER OMEGA WITH TITLO||CYRILLIC SMALL LETTER OMEGA WITH TITLO||CYRILLIC CAPITAL LETTER BROAD OMEGA||CYRILLIC SMALL LETTER BROAD OMEGA|
|UTF-8||209 160||D1 A0||209 161||D1 A1||209 188||D1 BC||209 189||D1 BD||234 153 140||EA 99 8C||234 153 141||EA 99 8D|
|Numeric character reference||Ѡ||Ѡ||ѡ||ѡ||Ѽ||Ѽ||ѽ||ѽ||Ꙍ||Ꙍ||ꙍ||ꙍ|
- A Berdnikov and O Lapko, "Old Slavonic and Church Slavonic in TEX and Unicode", EuroTEX ’99 Proceedings, September 1999 (PDF)