  The fixed point index of topological fixed point theory is a well studied
integer-valued algebraic invariant of a mapping which can be characterized by a
small set of axioms. The coincidence index is an extension of the concept to
topological (Nielsen) coincidence theory. We demonstrate that three natural
axioms are sufficient to characterize the coincidence index in the setting of
continuous mappings on oriented differentiable manifolds, the most common
setting for Nielsen coincidence theory.
