Every seafarer must have a seaman's discharge book. This book contains all key data on career experience and courses completed. The seaman's discharge book is a sort of passport for seafarers, which is required in order to apply for a Certificate of Competency. The seaman's book is the primary document for registration of crewmembers in the Central Register of Transport and Water Management Inspectorate (The Netherlands)
 
The inspectorate will only issue a seaman's book to persons who require it for their work, en has a employer's certificate for ocean going sevices. A seaman's book is only valid if it has been signed by the bearer and is considered invalid if unauthorised parties have altered it.