Describes the methods for deriving quality of service from network performance. Has been developed to: distinguish between quality of service and user option; provide descriptions of network performance and quality of service; describe the features of and the relationship between network performance, quality of service and user option; illustrate how the quality of service and the network performance concepts are applied in digital networks; identify generic performance parameters; distinguish between quality of service and user option; and indicate and classify performance concerns for which parameters may be needed.