time/leapseconds

   1 # @(#)leapseconds       7.7
   2
   3 # Allowance for leapseconds added to each timezone file.
   4
   5 # The International Earth Rotation Service periodically uses leap seconds
   6 # to keep UTC to within 0.9 s of TAI (atomic time); see
   7 # Terry J Quinn, The BIPM and the accurate measure of time,
   8 # Proc IEEE 79, 7 (July 1991), 894-905.
   9 # There were no leap seconds before 1972, because the official mechanism
  10 # accounting for the discrepancy between atomic time and the earth's rotation
  11 # did not exist until the early 1970s.
  12
  13 # The correction (+ or -) is made at the given time, so lines
  14 # will typically look like:
  15 #       Leap    YEAR    MON     DAY     23:59:60        +       R/S
  16 # or
  17 #       Leap    YEAR    MON     DAY     23:59:59        -       R/S
  18
  19 # If the leapsecond is Rolling (R) the given time is local time
  20 # If the leapsecond is Stationary (S) the given time is GMT
  21
  22 # Leap  YEAR    MONTH   DAY     HH:MM:SS        CORR    R/S
  23 Leap    1972    Jun     30      23:59:60        +       S
  24 Leap    1972    Dec     31      23:59:60        +       S
  25 Leap    1973    Dec     31      23:59:60        +       S
  26 Leap    1974    Dec     31      23:59:60        +       S
  27 Leap    1975    Dec     31      23:59:60        +       S
  28 Leap    1976    Dec     31      23:59:60        +       S
  29 Leap    1977    Dec     31      23:59:60        +       S
  30 Leap    1978    Dec     31      23:59:60        +       S
  31 Leap    1979    Dec     31      23:59:60        +       S
  32 Leap    1981    Jun     30      23:59:60        +       S
  33 Leap    1982    Jun     30      23:59:60        +       S
  34 Leap    1983    Jun     30      23:59:60        +       S
  35 Leap    1985    Jun     30      23:59:60        +       S
  36 Leap    1987    Dec     31      23:59:60        +       S
  37 Leap    1989    Dec     31      23:59:60        +       S
  38 Leap    1990    Dec     31      23:59:60        +       S
  39 Leap    1992    Jun     30      23:59:60        +       S
  40 Leap    1993    Jun     30      23:59:60        +       S
  41 Leap    1994    Jun     30      23:59:60        +       S