Bond of allegiance? The three lines on Dilmun seals

Stamp seals of the Dilmun type have kept their characteristic shape and boss decoration of three lines and four dotted circles for several 100 years. Although the carving of the shape of the seal and the design on the obverse normally reveal a confident experience, the cutting of the three lines on the reverse is generally irregular and clumsy. It is suggested that the former was in the hands of a professional seal carver, whereas the latter was carried out by the seal owner, perhaps as a sign of allegiance to the king.