This International Standard specifies the conventions to be used in numbering reference stations, waterlines, structural frames, transverse bulkheads, decks, compartments (holds, 'tween-decks, tanks), hatchways, masts and cargo-handling equipment where reference numbers are required for use in computer programs. It applies in particular to conventional mono-hull merchant ships, and may require adaptation for other configurations and for warships. The existence of this International Standard does not release the designers of computer programs from the obligation to provide flexibility to accommodate other conventions which may be required in particular circumstances but the conventions specified may be used as default options.