Hartley's rate result can be viewed as the capacity of an errorless M-ary channel of 2 B {\displaystyle 2B} symbols per second. Some authors refer to it as a capacity. But such an errorless channel is an idealization, and if M is chosen small enough to make the noisy channel nearly errorless, the result is necessarily less than the Shannon capacity of the noisy channel of bandwidth B {\displaystyle B} , which is the Hartley–Shannon result that followed later.