Guidance documents are the strongest documented consensus of how the directives are interpreted.Among the three guidance documents,NB-MED are the most useful documents.The duties of NB-MED are to receive technical dossier submitted by manufacturer,to assess the manufacturer quality management system,to evaluate evidences from lab ,clinical or animal studies.NB-MED also function as national standard institute and their division with responsibility may participate in writing ISO standards.NB-MED also as a part of contract of National competent authority should participate in vigilance in case they receive reports of adverse incident.If a device needs to be removed from market ,it is the responsibility of NB-MED to suspend its certificate.