Русско-англо-русский юридический словарь

A default rule is one that governs unless the parties contract out of it. In contrast, a mandatory rule is one that governs despite a contract term to the contrary, that is, a rule that cannot be avoided by contract. One can identify which laws are default and which are mandatory by examining the sorts of contract terms that are, and are not, enforceable. For example, the legal rule that the place for delivery in a sale of goods is the seller's place of business is a default rule because parties can make an enforceable contract requiring delivery at some other location. In contrast, the legal rule giving a consumer the right that goods purchased not be "in a defective condition unreasonably dangerous to the user" is mandatory because it applies no matter what the contract terms say. The distinction between mandatory and default rules is fundamentally important because it reveals the extent of contractual freedom. Mandatory rules limit the freedom of contract, while default rules permit it. (Arbitration Law in America: A Critical Assessment edited by Edward Brunet)

A default rule is one that governs unless the parties contract out of it. In contrast, a mandatory rule is one that governs despite a contract term to the contrary, that is, a rule that cannot be avoided by contract. One can identify which laws are default and which are mandatory by examining the sorts of contract terms that are, and are not, enforceable. For example, the legal rule that the place for delivery in a sale of goods is the seller's place of business is a default rule because parties can make an enforceable contract requiring delivery at some other location. In contrast, the legal rule giving a consumer the right that goods purchased not be "in a defective condition unreasonably dangerous to the user" is mandatory because it applies no matter what the contract terms say. The distinction between mandatory and default rules is fundamentally important because it reveals the extent of contractual freedom. Mandatory rules limit the freedom of contract, while default rules permit it. (Arbitration Law in America: A Critical Assessment edited by Edward Brunet)

intention to create legal relations One of the essential elements in the creation of a binding contract, this intention is implied by the fact that it is not expressly denied. If expressly denied (as in a so-called gentlemen's agreement) the contract may not be enforceable. (BusinessDictionary.com)

A memorandum of understanding (MoU) describes a bilateral or multilateral agreement between two or more parties. It expresses a convergence of will between the parties, indicating an intended common line of action. It is often used in cases where parties either do not imply a legal commitment or in situations where the parties cannot create a legally enforceable agreement. It is a more formal alternative to a gentlemen's agreement. (Wikipedia)