This International Standard specifies a method for the determination of the linear density of all types of yarn in package form, with the exception of any yarn that may be the subject of a separate International Standard1). It includes seven optional procedures based on different methods of conditioning and preparation (see 4.1 and 4.2). Since the different procedures do not give the same values, it is essential that the procedure used is agreed by all parties interested in the test results. While this method is designed solely for the determination of mass per unit length of yarn, it is frequently desirable to combine this determination with tests for strength and/or tests for commercial mass. If, in such a case, skein lengths other than those specified are used, the length used, and any special corrections based on it, are subject to agreement between the interested parties. This method is applicable to a) single yarns (spun, monofilament or multifilament); b) folded (plied) yarns; c) cabled yarns. It is not applicable, except by agreement, to yarns which stretch more than 0,5 % when the tension, in centinewtons, per unit linear density of yarn, in tex, increases from 0,5 to 1,0. Such yarns may be tested under special conditions if they are accepted by all the parties interested in the test results. The method is not applicable to yarns having a linear density greater than 2 000 tex. For such yarns, other skein lengths and special conditions of reeling may be adopted by agreement of the interested parties.