The main conditions of a contract are the price and the description of the object. The law requires certain types of contracts to be in writing to be enforceable. Contracts that must be in writing include contracts for the sale of land or any other interest associated with land, mortgages and powers of attorney. The rule of evidence in matters of parole provides that when a contract is in writing, the courts will not go beyond the contract, particularly with regard to the meaning of the words contained in the contract. According to the rule, words cannot be added to a written contract. A standard contract also requires the contractual relationship. This doctrine provides that only the parties to the contract can sue or be sued under the contract. A person who is not a party to the contract cannot enforce the terms of the contract. Professional secrecy provides that even if the contract is for the benefit of an individual, he can only execute it if he is a party to the contract. The terms of a standard contract may be expressly agreed between the parties at the time the contract is formed or may be implied by law or statute. Implied terms are terms that the parties intend to be included in the contract but which, for whatever reason, are not included in the contract. Certain terms are generally implied into all consumer contracts. These terms include fitness for purpose, merchantable quality, and correspondence to description or sample (Schwartz and Scott,