"Go, No-go" is a term used to indicate a condition of a part, component, system, etc., which can have only two states. "Go" indicates functioning properly; "No-go" means not functioning properly.
"Go, no-go" is also a term used in production and inspection and testing of components and systems for conformance to certain criteria such as diameter of a pin or a hole. Go-no-go gauges are common devices in production areas where mechanical parts are produced for example. Even mundane things like pellets and gravel are sorted by a series of so-called go-no-go screens.