Firms will attempt to reduce the number of jobs which are essential to their activities to the irreducible ‘core’. The distinguishing feature of core jobs is that they require skills which are specific to the firm and in which the firm often has an investment through training. Core employees will be drawn from primary labour markets and they will have relatively high wages and job security. Even within the core, however, firms will seek functional flexibility in the form of arrangements which allow labour to be switched from one activity to another