Orthogonal group:O(2,3)

You might be referring to:


 * Dihedral group:D8. This is the orthogonal group of degree two over field:F3 of type $$-1$$. It is also the one that corresponding to the standard dot product. It is denoted $$O(-1,2,3)$$ or $$\Omega(-1,2,3)$$.
 * Klein four-group: This is the split orthogonal group of degree two over field:F3. It is denoted $$O(+1,2,3)$$ or $$\Omega(+1,2,3)$$.