Classification means that a ship adheres to the Society's own Classification rules, in other words it is the appraisement of the level of compliance to the rules set up by the class society. This appraisement is represented by class marks and notations entered on a certificate and periodically transcribed in the classification society's register. Remark: It is not compulsory by law that a ship owner has his vessel built according to the rules of any classification society, but in practice , the difficulty in securing satisfactory insurance rates for an un-classed vessel makes it a commercial obligation