This object reports how long this bin's collection window spans, in minutes, as stated in the MIB description and its UNITS clause. For the History table this is expected to read a fixed 15 -- the device's configured 15-minute or 24-hour PM granularity -- so a value that deviates from that (e.g. a short bin right after a device reload) is itself diagnostic evidence that the collection interval for this specific egress queue on the port was interrupted rather than running its normal length. For example, seeing 14 instead of the expected 15 on this bin for this specific egress queue on the port would tell the admin the interval ran short, most likely because of a reboot or manual clear partway through.