periodically. If the counter exceeds a threshold upon being incremented, the network discards the packet. The user specifies the rate at which the counter is decremented (this determines the average bandwidth) and the value of the threshold (a measure of burstiness)". The bucket (analogous to the counter) is, in this case, used as a meter to test the conformance of packets, rather than as a queue to directly control them. Another description of what is essentially the same meter version of the algorithm, the generic cell rate algorithm, is given by the ITU-T in recommendation I.371 and in the ATM Forum's UNI Specification. The description, in which the term cell is equivalent to packet in Turner's description is given by the ITU-T as follows: "The continuous-state leaky bucket can be viewed as a finite capacity bucket whose real-valued content drains out at a continuous rate of 1 unit of content per time unit and whose content is increased by the increment T for each conforming cell... If at a cell arrival the content of the bucket is less than or equal to the limit value τ, then the cell is conforming; otherwise, the cell is non-conforming. The capacity of the bucket (the upper bound of the counter) is (T + τ)". These specifications also state that, due to its finite capacity, if the contents of the bucket at the time the conformance is tested is greater than the limit value, and hence the cell is non-conforming, then the bucket is left unchanged; that is, the water is simply not added if it would make the bucket overflow. David E. McDysan and Darrel L. Spohn provide a commentary on the description given by the ITU-T/ATM Forum. In this, they state "In the leaky bucket analogy, the [ATM] cells do not actually flow through the bucket; only the check for conforming admission does". However, uncommonly in the descriptions in the literature, McDysan and Spohn also refer to the leaky bucket algorithm as a queue, going on "Note that one implementation of traffic shaping is to actually have the cells flow through the bucket". In describing the operation of the ITU-T's version of the algorithm, McDysan and Spohn invoke a "notion commonly employed in queueing theory of a fictional 'gremlin'". This gremlin inspects the level in the bucket and takes action if the level is above the limit value τ : in policing