A description of the jobs in a labor force, an "occupational" description of it, is an abstraction for describing the flow of concrete work that goes through one or more employing organizations; the flow of work proba bly changes at a higher speed than the system for abstracting a descrip tion of its occupations and jobs. A career system is an abstraction for describing the flow of workers through a system of occupations or jobs, and thus is doubly removed from the flow of work. The federal civil service, however, ties many of the incentives and much of the authority to the flow of work...