In this paper, the $C^1$ interior of the set of all diffeomorphisms satisfying
the OE-property is characterized as the set of all diffeomorphisms satisfying Axiom
A and the strong transversality condition. Thus the $C^1$ interior of the set of all
diffeomorphisms satisfying the OE-property is equal to the $C^1$ interior of the set of
all diffeomorphisms satisfying the shadowing property.