However, not every Mealy machine can be converted to an equivalent Moore machine. Some can be converted only to an "almost" equivalent Moore machine, with outputs shifted in time. This is due to the way that state labels are paired with transition labels to form the input/output pairs. Consider a transition formula_21 from state formula_22 to state formula_23. The input causing the transition formula_21 labels the edge formula_25. The output corresponding to that input, is the label of state formula_22. Notice that this is the source state of the transition. So for each input, the output is already fixed before the input is received, and depends solely on the present state. This is the original definition by E. Moore. It is a common mistake to use the label of state formula_23 as output for the transition formula_21.