2.An index estimating total labour costs, excluding bonuses, where bonuses are defined by D.11112 in Annex II to Regulation (EC) No 1726/1999, shall be provided, broken down by economic activities defined by the Commission, and shall be based on the NACE Rev. 2 classification, taking into account the feasibility studies defined in Article 10. Those measures, designed to amend non-essential elements of this Regulation, inter alia, by supplementing it, shall be adopted in accordance with the regulatory procedure with scrutiny referred to in Article 12(3).