In Boeseke v. Boeseke (1974) 10 Cal.3d 844, the parties entered into an agreement based on the husband's opinion regarding the value of assets including real property whose actual values were unknown. (Boeseke, supra, 10 Cal.3d at p. 847.) The wife accepted the husband's opinion and did not request any facts regarding the value, the nature, or the extent of the assets. (Id. at p. 849.) She also agreed to a provision (against her attorney's advice) that the parties acknowledge the assets are of an "indefinite and speculative value" and that "neither party makes any representations to the other" as to their value. (Id. at p. 848.) Approximately 20 years later, after the husband's death, the wife learned the assets had more value at the time they entered into the agreement, and sought relief. (Ibid.) Boeseke denied the request and held: "During negotiation to settle marital property rights, fairness dictates the managing spouse be under no duty to evaluate the marital assets. And if the managing spouse does assert an opinion of value, he or she must be able to do so without warranty. Valuation, like designation of property as being either community or separate, is an issue on which reasonable views often differ, and in the absence of concealment of assets--or facts materially affecting their value--a property settlement agreement may not later be set aside solely on the basis of the managing spouse's inaccurate opinion of value or on his or her refusal to have rendered such an opinion." (Id. at p. 850.)