It is the duty of all carriers, their officers, agents, and employees to exert every reasonable effort to make and maintain contracts covering rates of pay, rules, and working conditions.

No carrier, its officers, or agents shall change the rates of pay, rules, or working conditions of its employees, as a class as embodied in agreements except in the manner prescribed in such agreements or in section 6 of the Railway Labor Act.

Section 5, Third, (e) of the Railway Labor Act requires all carriers to file with the National Mediation Board copies of all contracts in effect with organizations representing their employees, covering rates of pay, rules, and working conditions. Several thousand of such contracts are on file in the Board's Washington office and are available for inspection by interested parties.