6. When the board of directors may refuse to issue a registration certificate or when a case of revocation of registration is referred to the board of directors, the secretary shall notify the person concerned thereof at least 30 days prior to the date fixed for the rendering of the decision; such notice must indicate to the certificate holder the reasons justifying the refusal to issue or the revocation as well as the possibility, within this timeframe, to submit comments, including during a meeting, and, as the case may be, to produce documents to complete his file.