Русско-англо-русский юридический словарь

The radar system, known as “market surveillance,” monitors the purchase and sale of stocks — billions of shares a day — and is administered by FINRA, the Financial Industry Regulatory Authority, a self-regulatory organization for the brokerage industry. (The Washington Post)

The English requirement for consideration does not apply in Scotland, so it is possible to have a gratuitous contract, i.e. a contract where only one of the parties comes under any duties to the other (e.g. a contract to perform services for no consideration). If, however, consideration is given, as for example in a sales contract, the contract is said to be onerous. (Wikipedia)

Another civil law classification relates to the advantage each party expects to receive from the agreement. A contract, such as a sale of goods, in which both parties expect to receive an advantage in exchange for the service or item they provide, is considered onerous. A contract where one party provides an advantage without receiving anything in return, such as a donation, is a gratuitous contract. (Civil Law Contracts by Christopher Meldrum)

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)