ClockIntervalBase2
The interval included in message types Announce, Sync, Delay_Req, and Pdelay_Req as indicated in section 7.7.2.1 of [1]. The mean time interval between successive messages shall be represented as the logarithm to the base 2 of this time interval measured in seconds on the local clock of the device sending the message. The values of these logarithmic attributes shall be selected from integers in the range -128 to 127 subject to further limits established in an applicable PTP profile.