Digraphs are formed to signify sounds not covered by the main alphabet (e.g., ντ for /d/, μπ for /b/, or ου for /u/), or to represent diphthongs (e.g., αυ for /af/ and /av/).<ref name="alexandro" /> | Digraphs are formed to signify sounds not covered by the main alphabet (e.g., ντ for /d/, μπ for /b/, or ου for /u/), or to represent diphthongs (e.g., αυ for /af/ and /av/).<ref name="alexandro" /> |