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

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.

Each row is a group numbered as shown in this Sudoku-Centered figure.

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

Each column is a group numbered as shown in this Sudoku-Centered figure.

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

Each 3x3 square is a group numbered as shown in this Sudoku-Centered figure.

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

The centers of each 3x3 square are a group and are marked with '1st' in this Sudoku-Centered figure.

In a Sudoku-Centered puzzle, the centers of each 3x3 square are a group and are marked with '1st' in the figure above.