<<My TZTAB shows the following ...

        # New Zealand Stardard Time, New Zealand Daylight Time
        #
        NZST-12NZDT
        0 3 25-31 10 1985-2038 0   NZDT-13
        0 1 1-7   3  1985-2038 0   NZST-12

        Must be a later version?>>


Or an earlier one? We're on 5.5PP4, installed 3 March 98. The file is

FILE: TZTAB.LIB.SYS
...
NUM LABELS: 0                   CREATED : SAT, JAN  3, 1998,  8:06 PM
MAX LABELS: 0                   MODIFIED: SAT, JAN  3, 1998,  8:06 PM
DISC DEV #: 3                   ACCESSED: MON, APR  6, 1998,  3:25 PM

so I'm assuming that it's the one that came with PP4.

        <<Do you know what all the numbers mean?>>


The header is fairly obvious. The "meat" lines are comprised of seven
fields:
1)      The minute at which the zone change occurs, generally 0
2)      The hour at which the zone change occurs, generally 1 when
"springing forward" to DT and 3 when "falling back" to ST (those terms being
extremely northhemispherocentric, of course)
3)      The day of the month of the zone change; either this field or field
6 must be a range, and the other must not
4)      The month of the zone change
5)      The year of the zone change; may be a range
6)      The day of the week (0 == Sunday) of the zone change; either this
field or field 3 must be a range, and the other must not
7)      The zone name and offset from UTC

So, the line
  0 3 25-31 10 1985-2038 0   NZDT-13

says "change to New Zealand Daylight Time (NZDT), which differs from UTC by
-13 hours (-13) at 0300 (0 3) on the Sunday (0) that falls between the 25th
and 31st (25-31), inclusive,  of October (10) in each year between 1985 and
2038 (1985-2038), inclusive". Whew.

Steve