Bibi Khanum moskee - square pattern- ks
In this panel on the side wall of the pishtaq of the mosque four squares are grouped so that the kufic writing is rotated each time by 90° filled in turn by Allah and Ahad (one), so turning round in the square one can read Allah Ahad: there's just one God.
Colouring the first letter in both words dark blue (the dash in the pattern), groups the squares in one, without creating a continuous edge.