Explanation:

Collective bargaining is the formal process of negotiation between an employer and a group of employees—often with their union representative—that sets the terms and conditions of work.

While the NLRA—the law that applies to most private sector employees—does not include a list of bargaining topics, the National Labor Relations Board (NLRB) and courts determine which subjects are covered by the NLRA. They divide bargaining subjects into three categories: mandatory, permissive, and illegal. Mandatory subjects, broadly speaking, relate to wages, hours, pensions, healthcare and working conditions. Employers cannot refuse to bargain over these subjects, and negotiations may continue to the point of mediation or strike. Permissive subjects are non-mandatory subjects of bargaining, meaning employers are not required to bargain over them. Use of union labels is an example of a permissive bargaining subject.