Case C-377/21, Part-time Work

Is Clause 4 of the Framework Agreement implemented by Council Directive 97/81/EC of 15 December 1997 concerning the Framework Agreement on part-time work concluded by UNICE, CEEP and the ETUC to be interpreted as not precluding national legislation which, for the calculation of the salary of professional firefighters employed on a full-time basis, accredits, in respect of the length of service for financial purposes, the services provided on a part-time basis as a volunteer firefighter according to the volume of work, that is to say the duration of the services actually provided, in line with the principle of ‘pro rata temporis’, and not according to the period over which the services were provided?