Order of the Court (Tenth Chamber) of 23 April 2021.#Centre d’Enseignement Secondaire Saint-Vincent de Soignies ASBL v FS.#Request for a preliminary ruling from the Cour du travail de Mons.#Reference for a preliminary ruling – Article 53(2) and Article 99 of the Rules of Procedure of the Court – Social policy – Protection of the safety and health of workers – Organisation of working time – Directive 2003/88/EC – Maximum weekly working time – Reference period – Article 16 – Derogations – Articles 17 and 18 – Supervisor-teacher at a boarding school undertaking night duty – Compensatory rest conditions.#Case C-471/20.