55However, in order to be admissible, a request to amend the form of order sought must be submitted within the time-limit for bringing proceedings laid down in the sixth paragraph of Article 263 TFEU. It has consistently been held that the time‑limit for bringing proceedings is mandatory and must be applied by the Courts of the European Union in such a way as to safeguard legal certainty and equality of persons before the law (see Case C-229/05 PPKK and KNK v Council [2007] ECR I-439, paragraph 101). It is thus for the Courts to verify, if necessary of their own motion, whether that time-limit has been observed (see order of 11 January 2012 in Case T‑301/11Ben Ali v Council, not published in the ECR, paragraph 16).