This section is from the book "The Law Of Contracts", by William Herbert Page. Also available from Amazon: Commercial Contracts: A Practical Guide to Deals, Contracts, Agreements and Promises.
In order that a written contract may be treated as incomplete, so as to make extrinsic evidence of other terms admissible, it must show upon its face that it is incomplete.1 A written contract, such as a contract of sale,2 or an assignment,3 will be assumed to be complete unless it shows upon its face that it does not contain provisions as to certain necessary elements of the contract. The fact that a written contract does not provide for the point at which shipment is to begin, does not render it so incomplete as to justify explanation by extrinsic evidence.4 If a written contract contains a specific provision with reference to some subject,5 such as a provision for a warranty,6 it will be presumed that such written provision contains the entire agreement of the parties upon such topic. The fact that a contract does not provide for all the possible emergencies and contingencies which may arise in the future, is not sufficient to show that such contract is, upon its face, incomplete.7
1 Parker v. Law, 194 Ala. 693, 69 So. 879; Detroit Trust Co. v. Engel, 192 Mich. 62, 158 N. W. 123; A. B. Farqu-har Co. v. Hardy Hardware Co., 174 N. Car. 369, 93 S. E. 922; Ridgeway Dynamo & E. Co. v. Pennsylvania Cement Co., 221 Pa. St. 160, 18 L. R. A. (N.S.) 613, 70 Atl. 657.
2 Michigan. Detroit Trust Co. v. Engel, 192 Mich. 62, 158 N. W. 123.
North Carolina. A. B. Farquhar Co. v. Hardy Hardware Co., 174 N. Car. 369, 93 S. E. 922.
Pennsylvania. Ridgeway Dynamo & E. Co. v. Pennsylvania Cement Co., 221 Pa. St. 160, 18 L. R. A. (N.S.) 613, 70 Atl. 557.
South Dakota. Emerson-Branting -ham Implement Co. v. Edgar, 39 S. D. 139, 163 N. W. 575.
3 Parker v. Law, 194 Ala. 693, 69 So 879.
4Seymour v. Chicago & N. W. Ry. Co., 181 la. 218, 164 N. W. 352.
5 Seymour v. Chicago & N. W. Ry. Co., 181 Ia. 218, 164 N. W. 352.
1 Georgia. Brosseau v. Jacobs' Pharmacy Co., 147 Ga. 185, 93 S. E. 293.
Illinois. Telluride Power Transmission Co. v. Crane, 208 111. 218, 70 N. E. 319 [affirming, 103 111. App. 647].
Massachusetts. Glackin v. Bennett, 226 Mass. 316, 115 N. E. 490; Love-land v. Epstein Drug Co., 227 Mass. 311, 116 N. E. 570.
Nebraska. Roden v. Williams, 100 Neb. 46, L. R. A. 1917A, 415, 158 N. W. 360.
New York. Thomas v. Scutt, 127 N. Y. 133, 27 N. E. 961; Case v. Bridge Co., 134 N. Y. 78, 31 N. E. 254; Stowell v. Ins. Co., 163 N. Y. 298, 57 N. E. 480; Dady v. O'Rourke, 172 N. Y. 447,
65 N. E. 273; Brantingham v. Huff. 174 N. Y. 53, 95 Am. St. Rep. 545,
66 N. E. 620.
Oregon. Sund v. Flagg & Standifer Co., 86 Or. 289, 168 Pac. 300.
Washington. Van Doren Roofing & Cornice Co. v. Guardian Casualty & Guaranty Co., 99 Wash. 68, 168 Pac 1124; Thomson & Stacy Co. v. Evans, 100 Wash. 277, 170 Pac. 578.
Wisconsin. John O'Brien Lumber Co. v. Wilkinson, 117 Wis. 468, 94 N. W. 337; Foster v. Lowe, 131 Wis. 54, 110 N. W. 829.
A form of attack on the parol evidence rule, often so disguised as to be difficult of detection, consists in claiming that a written contract, complete on its face, is incomplete, and in offering to establish this by extrinsic evidence of terms not reduced to writing. This evidence is sought to be used both to show that the written contract is incomplete and to establish the terms of the contract not reduced to writing. This can not be done. The use of such evidence violates the spirit and purpose of the parol evidence rule.8 So under a complete written contract of sale extrinsic evidence is inadmissible to show sale by sample.9 So under a complete written contract for the sale of a boiler of certain specified dimensions for a tug, extrinsic evidence is inadmissible to show that the seller was to examine the tug and furnish the size of boiler neces-sary.10 The question of whether a written contract upon which suit is brought is complete or not is for the court.11 A contract may show upon its face that it is incomplete by express reference to written terms in another instrument which do not exist.12 A contract for the sale of realty, which purparts to be "on the terms specified on the back hereof," may be explained by oral evidence if no written terms appear upon the back of such contract.13 A contract may show on its face that it is incomplete by express reference to an oral agreement as part thereof without specifying what such oral agreement is.14 Thus "as per conversation,"15 "as per your conversation," 16 or "as per our conversation of yesterday,"17 or " as hereafter agreed,",18 shows that the contract is incomplete. If a written contract refers to the "system" under which the work is to be done, and such written contract does not explain what such system is, extrinsic evidence is admissible to show the oral statements of such parties as to the nature of such system.19 An express reference to a conversation as to one branch of a contract does not authorize the introduction of oral agreements upon another branch of such contract which vary the legal effect of other written provisions of such contract.20 A reference to conversations for purposes of identity does not authorize evidence of an oral agreement by which the seller undertakes to protect the buyer against the sale of articles which are claimed to infringe a patent.21 So a contract for advertisements which refers to "our contract price for glass other than we have estimated on, or contracted for, prior to the date hereof," and does not otherwise specify what that contract price is, is on its face incomplete by reason of the reference to such other contract, and such other contract may be enforced, though oral.22 A note which is given in performance of a contract and which does not on its face set forth the terms of the contract under which it is given, is not presumed to be complete, and extrinsic evidence may be admitted to show the remaining terms of such contract.23 Accordingly, evidence is admissible to show an agreement to pay the debt for which the note was given out of the proceeds of an insurance policy, thereby waiving exemptions as to such policy,24 or to show an oral warranty, by the payee, of the article sold,25 even if the note reserves title to the article until payment.26 A deed does not ordinarily purport to set forth in detail the terms of the contract, in performance of which it is given, and extrinsic evidence of the terms of the actual agreement is admissible as far as sucl terms are consistent with the express provisions of such deed.27 If the deed does not set forth the area of the property conveyed or the price to be paid therefor, extrinsic evidence is admissible to show the actual agreement between the parties as to the area agreed upon and the price per acre.28 A railroad ticket does not ordinarily set forth the agreement of the railroad company as to the time at which performance will be made, and accordingly extrinsic evidence of the actual agreement as to the time of performance may be considered.29 If the railway ticket makes no provision for stop-over privileges, oral evidence of the actual agreement as to such provision may be considered.30 A contract of sale which provides that the goods are to be "f. o. b.," is so incomplete upon its face that oral evidence may be offered to show the actual shipping directions.'1 So a writing intended only to secure a lien,32 or to make the price of a charge.33 neither of them prevent evidence of an oral warranty. So if a written order for shipping soap is made out by the vendor's agent, the vendee writing on it "accepted," and signing his name, the vendee may show that the contract was that all the soap was to be shipped to him, but that he was to take and pay for only one-half of it, the other half to be delivered by him to another druggist.34 A letter by which a purchaser orders certain goods, together with a bill of the goods, which are delivered, are not so formal as to raise a presumption that all prior negotiations are embodied in such written instrument.35 A letter which is written to authorize A to act as B's agent in purchasing certain property for B, will not be presumed to contain the agreement of the parties as to compensation, and B may show that such letter was written in reliance upon a prior oral arrangement on the part of A to perform such services gratuitously.36 A sheriff's return of a sale is so far incomplete that it may be shown that the purchaser bought for another lien-holder, and that conveyance was made under such arrangement.37 A memorandum may appear incomplete on its face by showing that a time of payment was fixed, but not showing what the time was,38 or where the memorandum shows only the purchase price and the time of payment.39 The use of "etc." does not of itself show that the contract is incomplete.40 If both parties to a written contract or memorandum agree that it is incomplete and that it omits certain terms upon which the parties had agreed expressly, oral evidence of the terms which the parties agree to have been omitted, may be offered, as long as such evidence does not contradict the terms of such contract which are reduced to writing.41