Under Rule 28(4)(a) and (b), until the date on which the technical preparations for publication of the application are deemed to have been completed, the applicant may inform the EPO that, until the publication of the mention of the grant of the European patent or, where applicable, for twenty years from the date of filing if the application has been refused or withdrawn or is deemed to be withdrawn, the availability referred to in Rule 28 is to be effected only by the issue of a sample to an expert.

The above communication must take the form of a written declaration addressed to the EPO. This declaration may not be contained in the description and the claims of the European patent application, but may be given in the Request for Grant form (Form 1001, Section 30).

If the declaration is admissible, it is mentioned on the front page when the European patent application is published (see also VI, 1.3).

If the applicant duly informs the EPO under Rule 28(4), the biological material is issued only to an expert recognised by the President of the EPO or approved by the applicant.

The list of recognised microbiological experts, giving their particulars and their fields of activity, is published in the Official Journal (see OJ 8/1992, 470).