This International Standard specifies two categories of method for the determination of the vinyl acetate (VAC) content of ethylene/vinyl acetate (EVAC) copolymers, for use in the designation of such copolymers in accordance with ISO 4613-1:1997. One category is referred to as "reference methods", the other as "test methods". Note – The abbreviation previously used for ethylene/vinyl acetate copolymer (E/VAC) has been replaced by the abbreviation EVAC (see ISO 1043-1:1997, Plastics – Symbols and abbreviated terms – Part 1: Basic polymers and their special characteristics). The "reference methods" are used to calibrate the method used for the determination of the vinyl acetate content of ethylene/vinyl acetate copolymers. The "test methods" are other methods which can be used for the determination if they are calibrated using one of the reference methods described in clause 3 provided they show a certain permissible repeatability