Joined Cases C-124/11, C-125/11 and C-143/11: Judgment of the Court (Third Chamber) of 6 December 2012 (references for a preliminary ruling from the Bundesverwaltungsgericht — Germany) — Bundesrepublik Deutschland v Karen Dittrich (C-124/11), Bundesrepublik Deutschland v Robert Klinke (C-125/11) and Jörg-Detlef Müller v Bundesrepublik Deutschland (C-143/11) (Equal treatment in employment and occupation — National rules — Assistance granted to public servants in the event of illness — Directive 2000/78/EC — Article 3 — Scope — Concept of ‘pay’ )