需求( Requirements) [IEEE Standard Glossary of Software Engineering 1990] (1)A condition or capability needed by a user to solve a problem or achieve an objective. (2 A condition or capability that must be met or possessed by a system or system component to satisfy a contract, standard specification or other formally imposed documents. (3A documented representation of a condition or capability as in(1 or(2)需求（ 什么是需求？ Requirements ） [IEEE Standard Glossary of Software Engineering 1990]: (1)A condition or capability needed by a user to solve a problem or achieve an objective. (2)A condition or capability that must be met or possessed by a system or system component to satisfy a contract, standard, specification, or other formally imposed documents. (3)A documented representation of a condition or capability as in (1) or (2)