Setting the time-of-day clock
Once the system has been initialized, it can issue one of two messages, depending on whether or not the time-of-day clock is set.
* 00 IEA886A TOD CLOCK(S) MUST BE SET
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If you include UTC in your reply, the time and date are Coordinated Universal Time. GMT is obsolete, but will be accepted as an alias of UTC. Without the UTC parameter the system assumes the values are local time and date, and only updates the local time of day offset without affecting UTC.
* id IEA888A UTC DATE=yyyy.ddd,CLOCK=hh.mm.ss
IEA888A LOCAL DATE=yyyy.ddd,CLOCK=hh.mm.ss REPLY U, OR UTC/LOCAL TIME
If the values are acceptable, reply ‘U’. If you want to change either the local date or time (or both) or the TOD clock, enter the new value(s) as follows, remembering that you must include the UTC parameter to change the value of the TOD clock:
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Again, the year yyyy must have four digits, and the apostrophes are optional.
If you specified a different clock setting, the system issues message IEA903A (which was described earlier). If you omitted UTC, the system assumes local date and/or time. Once you have set the new time and/or date, the system re-issues message IEA888A with new values. Reply to the message as described above.
Resetting UTC time causes the system to reset the TOD clock and recalculate the local time value, using the new UTC or GMT and the system time zone constant.
Resetting local time does not affect UTC time or the TOD clock. However, it will cause the system to recalculate the system time zone constant (which is initialized at IPL from the CLOCKxx parmlib member). The new time zone constant remains in effect until either local time is modified again or the next IPL.
All of the real time TQEs get adjusted when the local time is updated. Outstanding real time TQEs have their time adjusted based on the local time change that was made. For the External Timer Reference (ETR) or Server Time Protocol (STP), an external interrupt occurs with the time zone offset change, and the timer supervisor code invokes the same TQE time adjustment routine.
If message IEA888A indicates that both UTC and local time values are incorrect, reset the UTC value first.