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. 

A seaman's book will only be issued 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.