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适用范围：This British Standard describes an acceptance sampling systemprimarily designed for use under the following conditions:a) where the inspection procedure is to be applied to a continuingseries of lots of discrete products all supplied by one producerusing one production process;b) where only a single quality characteristic x of these products istaken into consideration, which must be measurable on a continuous scale;c) where the measurement error is negligible, i.e. with a standarddeviation no more than 10% of the process standard deviation;d) where production is stable (under statistical control) and thequality characteristic x is distributed according to a normaldistribution or a close approximation to the normal distribution;e) where a contract or standard defines a lower specification limitL, an upper specification limit U, or both; an item is qualifiedas conforming if and only if its measured quality characteristic xsatisfies the appropriate one of the following inequalities:1) x W L (i.e. the lower specification limit is not violated);2) x u U (i.e. the upper specification limit is not violated);3) x W L and x u U (i.e. neither the lower nor the upperspecification limit is violated). Inequalities 1) and 2) are called cases with a single specification limit, and 3) a case with double specification limits.Where double specification limits apply, it is assumed in this British Standard that conformance to both specification limits is equally important to the integrity of the product; in such cases, it is appropriate to apply a single AQL to the combined percentage of product outside the two specification limits. This is referred to as combined control.