20l blue canc. "ΤΡΙΠΟΛΙΣ*7.ΣΕΠΤ.78", double control numbes in a disntace 1.5mm vertically and horizontally with the second number printed lighter. In addition a third "0" approx. 1mm to the right. A case not mentioned in Koundouros study under 63.3 error. Fine - very fine and rare. (Hellas 51bNoI).