scope:

This International Standard is primarily designed for use under the following conditions: a) where the inspection procedure is to be applied to a continuing series of lots of discrete products all supplied by one producer using one production process. If there are different producers or production processes, this International Standard shall be applied to each one separately; b) where the quality characteristics of the items of product are measurable on a continuous scale. c) where the measurement error is negligible (i.e. with a standard deviation no more than 10% of the corresponding process standard deviation); d) where production is stable (under statistical control) and the quality characteristics are distributed, at least to a close approximation, according to normal distributions; e) where, in the case of multiple quality characteristics, the characteristics are independent of one another, at least approximately; f) where a contract or standard defines an upper specification limit U, a lower specification limit L, or both on each of the quality characteristics. If there is only one quality characteristic, an item is qualified as conforming if its measured quality characteristic x satisfies the appropriate one of the following inequalities: (i) x L ¡Ý (i.e. the lower specification limit is not violated); (ii) x U ¡Ü (i.e. the upper specification limit is not violated); (iii) x L ¡Ý andx U ¡Ü (i.e. neither the lower nor the upper specification limit is violated). If there are two or more, say m, quality characteristics, then, designating the upper and lower limits for the th i quality characteristic by i U and i L respectively, an item of product is qualified as nonconforming if one or more of its m measured quality characteristics i x fails to satisfy the appropriate one of the following inequalities: (iv) ;