См.: основной драйвер.
core drivercore driver - An entity, often at the bottom of a current reality tree, which does not have any cause(s) indicated. It is a descriptor of the environment and influences the problem area but is beyond the domain of management's control or influence or represents an entity that management does not want or is unable to address for some reason.
Illustration: In the CRT below, entities 15, 20 and 37 are core drivers. We may choose not to address entity 15 and we have no control over entities 20 and 37: