In Ptolemaic times the artaba (2336.), modified from the Persian, was general in Egypt, a working equivalent to the Attic metretes -- value 2 apet or 1/2 tama; medimnus=tama or 2 artabas, and fractions down to 1/400 artaba (35).
In Roman times the artaba remained (Didymus), but 1/6 was the usual unit (name unknown), and this was divided down to 1/24 or 1/144 artaba (35) -- thus producing by 1/12 artaba a working equivalent to the xestes and sextarius (35).
Also a new Roman artaba (Didymus) of (1540.) was brought in.
The absolute values being fixed by artaba = 51 Attic choenices (Herod.