Same shapes but with a dot in the center of the shape.
The process for generating and redeeming these codes is straightforward: sky code
Since "Sky Code" often refers to the friend invitation system in the game Sky: Children of the Light Same shapes but with a dot in the center of the shape
For numbers 0-9, use the bottom-right cell with X, and vary the number of dots or position of X? In games, numbers are often just A=1, B=2, etc., or a separate 4x4 grid. use the bottom-right cell with X