Only the digits 0, 1, 2, 5, 6, 8 and 9 are used, drawn in seven-segment form. Turned upside down (180° in the plane of the plate) 0, 1, 2, 5 and 8 stay the same while 6 and 9 change into each other, so 6 and 9 always come together. The upside-down square is the square turned by 180°: the last row comes first, each row is read backwards, each number is read backwards and 6 ↔ 9. In water or in a mirror 6 and 9 have no meaning, so these plates are only turned in their own plane.
Every entry is a chain of digit groups, one group per layer; in every layer each row, each column and both diagonals contain the same symbols. Turning the square sends rows to rows, columns to columns and diagonals to diagonals, and reading a number backwards with 6 ↔ 9 only rewrites each group with other digits — so the upside-down square is magic again.
3-digit cells: palindromic entries a·b·a where each Latin square fits in one digit (orders 4, 5 and 7), and three-layer entries a·b·c built algebraically for orders 4, 5, 7, 8, 10 and 14. Order 3 comes from a complete computer search: with 6 and 9 it has upside-down magic squares only with 3- and 4-digit cells and the digits (2,5,6,8,9), (0,1,2,5,6,9) and (0,1,2,5,6,8,9); the other families give semi-magic squares. Order 6 gives semi-magic squares.