[F1Article 11a U.K. Admissibility of complaints
1. Any person submitting a complaint pursuant to Articles 10(1) and 20(2) of Regulation (EC) No 659/1999 shall demonstrate that it is an interested party within the meaning of Article 1(h) of that Regulation.
2. Interested parties shall duly complete the form set out in Annex IV and provide all the mandatory information requested therein. On a reasoned request by an interested party, the Commission may dispense with the obligation to provide some of the information required by the form.
3. Complaints shall be submitted in one of the official languages of the Union.]