ISO 1081:2013 specifies the terms and definitions, in English and French, relating to V-belt drives, V-belts, hexagonal belts, joined V-belts and the corresponding V-grooved pulleys, V-ribbed belt drives, V-ribbed belts and V-ribbed pulleys, as well as the corresponding symbols.The general definitions are valid irrespective of the system describing the pulleys. The dimensions of pulley grooves can be defined either on the basis of the datum width or on the basis of the effective width. As a result, two systems for the definition and description of the dimensions of pulleys and belts have been developed. The two systems are independent of each other.