The initialization procedure is called upon reboot or restart of the NTP daemon. The local clock is presumably undefined at reboot; however, in some equipment an estimate is available from the reboot environment, such as a battery-backed clock/calendar. The precision variable is determined by the intrinsic architecture of the local hardware clock. The authentication variables are used only if the authentication mechanism described in Appendix C is implemented. The values of these variables are determined using procedures beyond the scope of NTP itself.