In relation to an establishment that is a factory, whom does the definition of "employer" in section 2(27) of the Code on Social Security, 2020 expressly include?

Section 2(27)(a) of the Code on Social Security, 2020 includes, for a factory, the occupier of the factory; the definition also includes a contractor and the legal representative of a deceased employer. The owner, agent or qualified manager is named only for a mine under clause (b), and neither the landowner nor a holding company is included.