Within four months of filing the European patent application, the applicant shall file the certificate referred to in Article 55, paragraph 2, which:
(a) is issued at the exhibition by the authority responsible for the protection of industrial property at that exhibition;
(b) states that the invention was in fact displayed there;
(c) states the opening date of the exhibition and, where the invention was disclosed later than on that date, the date on which the invention was first disclosed; and
(d) is accompanied by an identification of the invention, duly authenticated by the above-mentioned authority.