66More specifically, under the principle of equal treatment as between tenderers, which is merely a specific expression of the principle of equal treatment (see, to this effect, Case C-458/03Parking Brixen [2005] ECR I-8585, paragraphs 46 and 48 and the cited case‑law, and Case T‑332/03European Service Network v Commission, not published in the ECR, paragraph 72) and the aim of which is to promote the development of healthy and effective competition between undertakings taking part in a public procurement procedure, all tenderers must be afforded equality of opportunity when formulating their tenders, which therefore implies that the tenders of all competitors must be subject to the same conditions (Case C-496/99 PCommission v CAS Succhi di Frutta [2004] ECR I-3801, paragraph 110). Accordingly, the contracting authority must, at each stage of the tendering procedure, act in accordance with the principle of equal treatment of tenderers (Case T-203/96Embassy Limousines & Services v Parliament [1998] ECR II-4239, paragraph 85) and tenderers must be in a position of equality both when they formulate their tenders and when those tenders are being assessed by the contracting authority (see, to this effect, Case C-213/07Michaniki [2008] ECR I-9999, paragraph 45, and Case C‑251/09Commission v Cyprus, not published in the ECR, paragraph 39 and the cited case‑law).