Case T-212/20: Order of the General Court of 6 September 2023 — Gaz-System v ACER (Action for annulment — Energy — Regulation (EU) 2017/459 — Capacity allocation mechanisms in gas transmission systems — Selection of gas transmission capacity booking platforms — ACER decision in the absence of agreement between the national regulatory authorities — Selection procedure by ACER — Conditions for ACER to resume the proceedings after referral back by the Board of Appeal — Scope and intensity of the Board of Appeal’s review of the legality of ACER decisions — Manifestly well-founded action)