Write 9 Sentences For Your Response: What is an option contract? (is it more than one contract?) do you revoke an offer? Are the Mailbox and Mirror Image rules essentially non-issues in today's modern society being replace with issues such as whether online bids/offers constitute acceptance? Revocation of Offers for Unilateral Contracts. A problem arises in unilateral contracts when the promisor attempts to revoke (cancel) the offer after the promisee has begun performance but before the act has been completed. EXAMPLE 8.3 Seiko offers to buy Jin's sailboat, moored in San Francisco, on delivery of the boat to Seiko's dock in Newport Beach, three hundred miles south of San Francisco. Jin rigs the boat and sets sail. Shortly before his arrival at Newport Beach, Jin receives a message from Seiko withdrawing her offer. Was the offer terminated? In contract law, offers are normally revocable (capable of being taken back, or canceled) until accepted. Thus, under the traditional view of unilateral contracts, in Example 8.3, Seiko's revo- cation would terminate the offer. Because Seikos offer was to form a unilateral contract, only Jin's delivery of the sailboat at her dock would have been an acceptance. Because of the harsh effect on the offeree of the revocation of an offer to form a unilateral contract, the modern-day view is different. Today, once performance has been substantially undertaken the offeror cannot revoke the offer. Thus, in Example 8.3, even though Jin has not yet accepted the offer by complete performance, Seiko is prohibited from revoking it. Jin can deliver the boat and bind Seiko to the contract. Formal versus Informal Contracts Another classification system divides contracts into for- mal contracts and informal contracts. Formal contracts are contracts that require a special form or method of creation (formation to be enforceable. One example is negotiable instru- ments, which include checks, drafts, promissory notes, and certificates of deposit. Negotiable instruments are formal contracts because, under the Uniform Commercial Code, a special form and language are required to create them. Letters of credit, which are frequently used in international sales contracts, are another type of formal contract. Informal contracts (also called simple contracts) include all other contracts. No special form is required (except for certain types of contracts that must be in writing). The contracts are usually based on their substance rather than their form. Typically, though, businesspersons put their contracts in writing to ensure that there is some proof of a contracts existence should problems arise