The head movement in the output of the transition relation is often encoded numerically instead of using letters to represent moving the head Left (-1), Stationary (0), and Right (+1); giving a transition function output of \left( Q \times \Sigma \times \{-1,0,+1\} \right). It is common to omit the stationary (0) output, and instead insert the transitive closure of any desired stationary transitions.
