Case C-151/10: Order of the Court (Sixth Chamber) of 7 April 2011 (reference for a preliminary ruling from the Arbeidshof te Antwerpen (Belgium)) — Dai Cugini NV v Rijkdienst voor Sociale Zekerheid (First subparagraph of Article 104(3) of the Rules of Procedure — Directive 97/811/EC — Equal treatment of part-time and full-time workers — Discrimination — Administrative obstacle likely to limit the opportunities for part-time work — Mandatory publication and retention of contracts and work-schedules)