28The preservation of the effectiveness of that procedure is not made impossible in practice or excessively difficult by a national rule which makes it possible, between the date on which a request for a preliminary ruling is made to the Court and the date of the order or judgment by which the Court answers that request, to continue the main proceedings in order to carry out procedural steps, which the referring court considers necessary and which concern aspects unrelated to the questions referred for a preliminary ruling, namely procedural steps which are not such as to prevent the referring court from complying, in the main proceedings, with that order or that judgment.