The concept of Shamrock Organisations was outlined by Irish academic Charles Handy in his 1989 book The Age of Unreason to describe the three major component workforces of any organisation (the leaves of the Shamrock). These are: core workers, contract workers and peripheral workers, and all must interconnect seamlessly to create an efficient and productive organisation. This organisational culture model can be used to map the structure of a company, and can act as an aid in planning intra-company change and development.
John Atkinson's Flexible-Firm Model (1984) is a managerial and organisational technique used to optimise the allocation of human resources in accordance with market instability and workforce flexibility. It defines two clear groups of workers, the core and peripheral group, which are organised within the company based on three types of flexibility: functional, financial and numerical.