In all other groups, one letter occurs twice.

In all other groups, the second, third and fourth letters respectively three, five and seven steps ahead of the first , second and third letters respectively.

In all other groups, the numbers are in the ratio 1 : 3 : 2 : 5

In all other pairs, sum of the two numbers is 8.

In all other groups, the fourth, first and third letters are alternate letters in order.

All other groups contain four consecutive letters in reverse alphabetical order.

In all other groups, the first and second as well as the third and fourth letters are alternate, and the third letter is three steps ahead of the second letter.