/sys$common/syshlp/helplib.hlb Sys Parameters, TIMEPROMPTWAIT  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    TIMEPROMPTWAIT defines the number of seconds that you want a
    processor to wait for the time and date to be entered when a
    system boot occurs, if the processor's time-of-year clock does
    not contain a valid time. (The time unit of micro-fortnights
    is approximated as seconds in the implementation.) If the
    time specified by TIMEPROMPTWAIT elapses, the system continues
    the boot operation, and the date and time are set to the last
    recorded time that the system booted.

                                   NOTE

       Compaq recommends that you set the correct system time
       before allowing the system to run, so that all functions
       using time-stamping (such as the operator log, the error
       log, accounting records, file creation dates, and file
       expiration dates) contain correct time values.

    Depending on the value specified for the TIMEPROMPTWAIT
    parameter, the system acts in one of the following ways:

    o  If TIMEPROMPTWAIT is 0, no prompt or wait occurs; the system
       boots immediately, using the time of the last boot as the
       system time.

    o  If TIMEPROMPTWAIT is a positive number less than 32768, one
       prompt is issued and the value dictates how many seconds you
       can take to respond with a time. If you do not provide a time
       before TIMEPROMPTWAIT elapses, the system boots, using the
       time of the last boot as the system time.

    o  If TIMEPROMPTWAIT is a number in the range of 32768 through
       65535, the prompt for the time is issued at intervals starting
       with 2 and doubling until 256 seconds is reached. If no
       response is received, the prompts restart, with the 2-second
       interval. This prompting process repeats indefinitely, until
       you specify a time.