Detailed instructions for working a group puzzle of type 'Doug'

This is a signature puzzle named 'Doug'

The 4 elements in each group of this type of puzzle are: D, O, U, and G.

Every group in the puzzle must contain exactly this set of elements.

Each row is a group numbered as shown in this Doug figure.

In a Doug puzzle, each row is a group numbered as shown in the figure above.

Each column is a group numbered as shown in this Doug figure.

In a Doug puzzle, each column is a group numbered as shown in the figure above.

Each 2x2 square is a group numbered as shown in this Doug figure.

In a Doug puzzle, each 2x2 square is a group numbered as shown in the figure above.