What is the test for a de novo review of a marital settlement agreement?

As in this case, where "no conflicting extrinsic evidence is offered of an interpretation as to which the language of a marital settlement agreement is reasonably susceptible, and the facts are otherwise undisputed, we apply the unambiguous contract terms to the undisputed facts as a matter of law." (In re Marriage of Iberti (1997) 55 Cal.App.4th 1434, 1439; Messenger v. Messenger (1956) 46 Cal.2d 619, 626.) The parties agree that de novo review is appropriate.