The decision to initiate the formal investigation procedure shall summarise the relevant issues of fact and law, shall include a preliminary assessment of the Commission as to the aid character of the proposed measure and shall set out the doubts as to its compatibility with the internal market. The decision shall call upon the Member State concerned and upon other interested parties to submit comments within a prescribed period which shall normally not exceed 1 month. In duly justified cases, the Commission may extend the prescribed period.

The comments received shall be submitted to the Member State concerned. If an interested party so requests, on grounds of potential damage, its identity shall be withheld from the Member State concerned. The Member State concerned may reply to the comments submitted within a prescribed period which shall normally not exceed 1 month. In duly justified cases, the Commission may extend the prescribed period.