Family Code section 4336, subdivision (a) provides: "Except on written agreement of the parties to the contrary or a court order terminating spousal support, the court retains jurisdiction indefinitely in a proceeding for dissolution of marriage or for legal separation of the parties where the marriage is of long duration." A 10-year marriage is presumed to be of long duration for purposes of retaining jurisdiction. (Fam. Code, 4336, subd. (b).) In In re Marriage of Ousterman (1996) 46 Cal.App.4th 1090, the order provided for spousal support for a specified period of time and further provided that support could not be modified on or before the end of that period. The husband conceded that under Family Code section 4336 the court had jurisdiction to extend spousal support after the specified date because the order did not expressly terminate jurisdiction. ( Id. at p. 1094.)