What is the test for establishing an agreed boundary?

These considerations and rules guide the result in the case at bench. Given the state of the evidence, and the burden of proof, we conclude that the trial court could reasonably have found that the defendant's case fell short of establishing uncertainty of the boundary, or for that matter, marking the agreed boundary or an agreement to establish a common boundary. (On the latter point, see Berry v. Sbragia (1978) 76 Cal.App.3d 876, 881, 143 Cal.Rptr. 318; where record shows no agreement as to boundary location, agreed boundary doctrine is inapplicable.)