Safran SecureSync 2400 User Manual page 596

APPENDIX
Where:
Leap Second Sign:
Leap Second Month:
Leap Second Zone:
GPS Week:
GPS Second:
GPS to UTC offset:
Checksum:
580
01=Positive
FF=Negative
00=No leap second
00=None scheduled
03=March
06=June
09=September
0C=December
0=Out of zone
1=Within zone
Zone is 15 minutes before to 15 minutes after a leap second.
Up to FFFF
Second of week 000000 up to 093A7F (604799 decimal)
2's complement binary signed integer, seconds
Sum of all bytes up to and including the checksum (sum includes the AAAA
start identifier but excludes the 9999 end identifier)
SecureSync 2400 User Manual