Source: http://www.west.net/~smith/interpret-content.htm
Timestamp: 2019-04-20 18:31:11+00:00

Document:
In the case of Raffles v. Wichelhaus (1864) 159 Eng.Rep. 375, the seller agreed to sell cotton to the buyer. Shipment was to made from Bombay on the ship named Peerless. However, there were two ships named "Peerless." One was to sail in October and the other in December. Defendants intended to accept the cotton on the ship that sailed in October and refused to accept the cotton on the ship that sailed in December. It was held by the court that there was no binding or enforceable contract. The rule of the Peerless case is that no contract arises unless both parties have the same meaning in mind. I.e., there must be agreement on the same thing. (Rest.2d §20).
Contract Construed Most Strictly Against Drafter Any ambiguities caused by the drafter of the contract must be resolved against the drafter or the party employing him or her. ( Cal.Civ.Code §1654; United States v. Seckinger, 397 U.S. 203 (1970)).
"Usage of Trade" (See, UCC 1-303 ) Technical words in a contract must "be interpreted as usually understood by persons in the profession or business to which they relate, unless clearly used in a different sense." ( Cal.Civ. Code §1645).
What happens when the parties omit a term from their contract? Rest.2d § 204 provides that when the parties omit a term from their contract which is essential to the determination of their rights the court will supply a term which is reasonable. If the contract is for the sale of goods Article 2 of the UCC provides for a number of statutory terms to be used to fill gaps in the contract when missing terms cannot be supplied through resort to course of performance, course of dealing or usage of trade. By setting forth statutory terms, the Code supplies the commonly accepted term on the matter and prevents the contract from failing for lack of a reasonable basis for enforcement. In case of conflict statutory terms are subordinated in rank to course of performance, course of dealing, and usage of trade.
Where the parties have reduced their agreement to final written form, evidence of prior or contemporaneous agreements is inadmissible to vary or contradict the terms of the final written agreement. ( Cal.Code.Civ.Proc. § 1856(a), see also Rest.2d § 213 Cal.Civ.Code § 1625 & UCC 2-202) The thrust of the parol evidence rule is that if the court finds the writing to have been intended as a complete and exclusive statement of the terms of the parties' agreement, then the writing alone constitutes the contract and evidence of prior negotiations or "side agreements" will not be resorted to in interpreting the final written agreement.
When the parties to a written contract have agreed to it as an "integration"--a complete and final embodiment of the terms of an agreement-- parol evidence cannot be used to add to or vary its terms.
When only part of the agreement is integrated, the same rule applies to that part, but parol evidence may be used to prove elements of the agreement not reduced to writing.

References: v. 
 §20
 §1654
 v. 
 §1645
 § 204
 § 1856
 § 213
 § 1625