The number of previous 15-minute intervals for which data was
collected. A SONET/SDH interface must be capable of supporting at
least n intervals. The minimum value of n is 4. The default of n is
32. The maximum value of n is 96. The value will be <n> unless the
measurement was (re-)started within the last (<n>*15) minutes, in which
case the value will be the number of complete 15 minute intervals for
which the agent has at least some data. In certain cases (e.g., in the
case where the agent is a proxy) it is possible that some intervals
are unavailable. In this case, this interval is the maximum interval
number for which data is available.