20l blue (pos.19), "0" inverted on control number with the "2" higher (Kound. 38.2+38.7). Position not mentioned in Koundouros study under 38.7 case. We find uneven control numbers on these 20 lepta stamps on postitions where the digit "0" was set inverted but not in all sheets. Impressive and uncommon. (Hellas 27aNb).