Case C-471/20: Order of the Court (Tenth Chamber) of 23 April 2021 (request for a preliminary ruling from the Cour du travail de Mons — Belgium) — Centre d’Enseignement Secondaire Saint-Vincent de Soignies ASBL v FS (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)