As defined in the Act, the term “enterprise” is roughly descriptive of a business rather than of an establishment or of an employer although on occasion the three may coincide. The enterprise, however, is not necessarily coextensive with the entire business activities of an employer. The enterprise may consist of a single establishment which may be operated by one or more employers; or it may be composed of a number of establishments which may be operated by one or more employers. On the other hand, a single employer may operate more than one enterprise. The Act treats as separate enterprises different businesses which are unrelated to each other and lack any common business purpose, even if they are operated by the same employer.