A modified union
The answer is: Modified Union
A union closed shop is a workplace in which only union workers are allowed and to work and an open shop allows non union workers
This question needs to be rewritten. I can think of union terms for "open/closed" shops, but I am not sure this is what you want.
A business that will not employ non-union workers is called a "closed shop".
Open Shop.
An open shop is a business that does not require union membership to be an employee.
Union shop.
open shop
It is a closed shop.
The agency-shop policy allows both union and nonunion workers to be employed by an organization, but the nonunion employees must pay a union fee equal to union dues.
Right to work laws allow workers to work in a union shop without joining the union. Thereby prohibiting workers to be forced to join a union.