 9600/ARQ/V32/LAPM/V42BIS

National Institute of Standards and Technology
Telephone Time Service, Generator 1a
Enter the question mark character for HELP
                        D  L
 MJD  YR MO DA HH MM SS ST S UT1 msADV         <OTM>

50859 98-02-15 21:55:10 00 0 +.2 045.0 UTC(NIST) *
50859 98-02-15 21:55:11 00 0 +.2 045.0 UTC(NIST) *
50859 98-02-15 21:55:12 00 0 +.2 045.0 UTC(NIST) *
50859 98-02-15 21:55:13 00 0 +.2 045.0 UTC(NIST) *
                               DESCRIPTION OF THE
                      AUTOMATED COMPUTER TIME SERVICE (ACTS)

The service uses multi-speed modems which should automatically adapt to
the speed of the originating modem.  All messages are sent using standard
ASCII characters with 8 bits, no parity and 1 stop bit.

Format of the time message:

                                     D  L D
              MJD  YR MO DA H  M  S  ST S UT1 msADV        <OTM>
             47999 90-04-18 21:39:17 50 0 +.1 045.0 UTC(NIST) *
             47999 90-04-18 21:39:18 50 0 +.1 045.0 UTC(NIST) *
             etc...

     The message transmits Universal Coordinated Time (UTC), the
official world time referred to the zero meridian of longitude.

The MJD is the modified Julian Day number, which advances by 1 at 0000 
UTC every day.

The DST parameter provides information about Daylight Saving Time, using 
the model valid for the continental US:

  00 = US is on standard time (ST).    50 = US is on DST.
  99 to 51 = Now on ST, go to DST when your local time is 2:00 am and the
             count is 51.  The count is decremented daily at 00 (UTC).
  49 to 01 = Now on DST, go to ST when your local time is 2:00 am and the
             count is 01.  The count is decremented daily at 00 (UTC).

LS = Leap second flag is set to "1" to indicate that a leap second is to be
added as 23:59:60 UTC on the last day of the current month (usually June or
December).  The flag will be set to "2" if the last second of the current 
month is to be dropped. The second following 23:59:58 UTC on the last day 
of the month will be 00:00:00 of the next day in that case.  The flag will
remain on for the entire month before a leap-second event; it will be 0 
otherwise.

DUT1 = Approximate difference between earth rotation time (UT1) and UTC, in
steps of 0.1 second.         DUT1 = UT1 - UTC

The specified time is valid when the "*" on-time marker is received.  This
character will be transmitted 45 ms early to compensate for the nominal
delay in the modems and the telephone connection.

The maximum connection time will be 40 seconds unless you transmit a 
"%" character before then.  If this character is received, the transmitter 
will break the connection at the next on-time marker.

For more information write:
NIST-ACTS
Time and Frequency Division
Mail Stop 847
325 Broadway
Boulder, CO  80303

e-mail: time@time.nist.gov

Software for setting (PC)DOS compatible machines is available
on a 360-kbyte diskette for $42 from:
Office of Standard Reference Materials
NIST, Gaithersburg, MD, 20899, (301) 975-6776

The software and additional information are also available 
on the internet via anonymous ftp from time_a.timefreq.bldrdoc.gov.


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