** Detailed instructions for working a group puzzle of type 'Sudoku-Xtreme' **

The 9 elements in each group of this type of puzzle are: **1**, **2**, **3**, **4**, **5**, **6**, **7**, **8**, and **9**.

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

In a Sudoku-Xtreme puzzle, each row in the upper left, upper right, lower left, and lower right puzzles is a group numbered as shown in the figure above.

In a Sudoku-Xtreme puzzle, each column in the upper left, upper right, lower left, and lower right puzzles is a group numbered as shown in the figure above.

In a Sudoku-Xtreme puzzle, each 3x3 square in the upper left, upper right, lower left, and lower right puzzles is a group numbered as shown in the figure above.

In a Sudoku-Xtreme puzzle, each diagonal in the upper left, upper right, lower left, and lower right puzzles is a group numbered as shown in the figure above.

In a Sudoku-Xtreme puzzle, each row in the center puzzle is a group numbered as shown in the figure above.

In a Sudoku-Xtreme puzzle, each column in the center puzzle is a group numbered as shown in the figure above.

In a Sudoku-Xtreme puzzle, each 3x3 square in the center puzzle is a group numbered as shown in the figure above.