  Reversible Boolean Circuits are an interesting computational model under many
aspects and in different fields, ranging from Reversible Computing to Quantum
Computing. Our contribution is to describe a specific class of Reversible
Boolean Circuits - which is as expressive as classical circuits - as a
bi-dimensional diagrammatic programming language. We uniformly represent the
Reversible Boolean Circuits we focus on as a free 3-category Toff. This
formalism allows us to incorporate the representation of circuits and of
rewriting rules on them, and to prove termination of rewriting. Termination
follows from defining a non-identities-preserving functor from our free
3-category Toff into a suitable 3-category Move that traces the "moves" applied
to wires inside circuits.
