What is the test for using parol evidence to determine the meaning of the word "parol" in the California Civil Code?

Civil Code, 1651, is also cited. It is the rule that where ambiguity appears in the language used in a written instrument, parol evidence may be used to show the true significance of the language, and notwithstanding the statutory presumption, the court will adopt the more reasonable interpretation. (Perkins v. Maiden, 57 Cal.App.2d 46, 134 P.2d 30.) See also Henneberry v. Henneberry, 164 Cal.App.2d 125, 330 P.2d 250.

[203 Cal.App.2d 108]