The acceptable quality limit (AQL) is the worst tolerable process average in percentage or ratio, that is still considered acceptable: that is, it is at an acceptable quality level. Closely related terms are the rejectable quality limit and level (RQL). In a quality control procedure, a process is said to be at an acceptable quality level if the appropriate statistic used to construct a control chart does not fall outside the bounds of the acceptable quality limits. Otherwise, the process is said to be at a rejectable control level.