• Tertrominoes are observed (or) assumed as if they are fixed into only being in "Orthogonal" rotations.
  • "Orthogonal" refers to being lined up with the horizontal and vertical axes.
  • Mirror symmetry can occur only along \(2\) axes.
  • Reflection along the horizontal axes is called the \(X\)-Reflection.
  • Reflection along the vertical axes is called the \(Y\)-Reflection.
  • Every tetromino can have \(1\) of \(4\) possible symmetries. ("Symmetric with \(Y\)" (or) "Symmetric with \(X\)" (or) "Symmetric to both" (or) "Asymmetric").