S₂/X₂

0

1

2

3

4

5

6

$f_2^{\ast }$

$X_2^{\ast }$

0

0

0

0

1

3

3

3

0 or 1

2

6

6

3

6

0 or 1

3

6

9

6

3

9

1

4

6

9

9

6

3

9

1 or 2

5

6

9

9

9

6

3

9

1, 2 or 3

6

6

9

9

9

9

6

3

9

1, 2, 3 or 4