On the Unresolved Question About the Debate Rules

How will the moderators address Trump? Will they call him President, former President, or just Mr.? The first approach puts the candidates on equal footing but plays into Trump’s argument that he is still the lawful president. The latter two would probably make him crazy and cause him to lash out.

Was this even addressed in the rules? I haven’t seen any reference to an agreement on that point. It matters.