"The Aleppo Codex" Aaron ben Moses ben Asher (10th century, died c.960) was a Jewish scribe who refined the Tiberian system of writing vowel sounds in Hebrew, which is still in use today, and serves as the basis for grammatical analysis. Aaron ben Asher added vowelization and cantillation notes, and mesorah to the Aleppo Codex, correcting its letter-text according to the masorah.