and non-steel hull construction; passenger ships of less than 100 gt, high-speed passenger craft and mobile offshore drilling units [...]; and all motorized inboard fishing vessels of less than 100 gt down to a size limit of 12 metres in length overall (LOA), authorized to operate outside waters under the national jurisdiction of the flag State". IMO resolutions are "for implementation on a voluntary basis".

Although not mandatory under SOLAS, since IMO ship numbers became available also