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TZFILE(5)                   BSD Programmer's Manual                  TZFILE(5)

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    t\btz\bzf\bfi\bil\ble\be - time zone information

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    #\b#i\bin\bnc\bcl\blu\bud\bde\be <\b<t\btz\bzf\bfi\bil\ble\be.\b.h\bh>\b>

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    The time zone information files used by tzset(3) begin with bytes re-
    served for future use, followed by four four-byte values of type _\bl_\bo_\bn_\bg,
    written in a ``standard'' byte order (the high-order byte of the value is
    written first).  These values are, in order:

    _\bt_\bz_\bh_\b__\bt_\bt_\bi_\bs_\bs_\bt_\bd_\bc_\bn_\bt  The number of standard/wall indicators stored in the
                    file.

    _\bt_\bz_\bh_\b__\bl_\be_\ba_\bp_\bc_\bn_\bt     The number of leap seconds for which data is stored in
                    the file.

    _\bt_\bz_\bh_\b__\bt_\bi_\bm_\be_\bc_\bn_\bt     The number of "transition times" for which data is stored
                    in the file.

    _\bt_\bz_\bh_\b__\bt_\by_\bp_\be_\bc_\bn_\bt     The number of "local time types" for which data is stored
                    in the file (must not be zero).

    _\bt_\bz_\bh_\b__\bc_\bh_\ba_\br_\bc_\bn_\bt     The number of characters of "time zone abbreviation
                    strings" stored in the file.

    The above header is followed by _\bt_\bz_\bh_\b__\bt_\bi_\bm_\be_\bc_\bn_\bt four-byte values of type
    _\bl_\bo_\bn_\bg, sorted in ascending order.  These values are written in ``stan-
    dard'' byte order.  Each is used as a transition time (as returned by
    time(2))  at which the rules for computing local time change.  Next come
    _\bt_\bz_\bh_\b__\bt_\bi_\bm_\be_\bc_\bn_\bt one-byte values of type _\bu_\bn_\bs_\bi_\bg_\bn_\be_\bd _\bc_\bh_\ba_\br; each one tells which
    of the different types of ``local time'' types described in the file is
    associated with the same-indexed transition time.  These values serve as
    indices into an array of _\bt_\bt_\bi_\bn_\bf_\bo structures that appears next in the file;
    these structures are defined as follows:

          struct ttinfo {
                  long    tt_gmtoff;
                  int     tt_isdst;
                  unsigned int    tt_abbrind;
          };

    Each structure is written as a four-byte value for _\bt_\bt_\b__\bg_\bm_\bt_\bo_\bf_\bf of type
    _\bl_\bo_\bn_\bg, in a standard byte order, followed by a one-byte value for _\bt_\bt_\b__\bi_\bs_\bd_\bs_\bt
    and a one-byte value for _\bt_\bt_\b__\ba_\bb_\bb_\br_\bi_\bn_\bd. In each structure, _\bt_\bt_\b__\bg_\bm_\bt_\bo_\bf_\bf gives
    the number of seconds to be added to GMT, _\bt_\bt_\b__\bi_\bs_\bd_\bs_\bt tells whether _\bt_\bm_\b__\bi_\bs_\bd_\bs_\bt
    should be set by localtime(3) and _\bt_\bt_\b__\ba_\bb_\bb_\br_\bi_\bn_\bd serves as an index into the
    array of time zone abbreviation characters that follow the _\bt_\bt_\bi_\bn_\bf_\bo struc-
    ture(s) in the file.

    Then there are _\bt_\bz_\bh_\b__\bl_\be_\ba_\bp_\bc_\bn_\bt pairs of four-byte values, written in standard
    byte order; the first value of each pair gives the time (as returned by
    time(2))  at which a leap second occurs; the second gives the _\bt_\bo_\bt_\ba_\bl num-
    ber of leap seconds to be applied after the given time.  The pairs of
    values are sorted in ascending order by time.

    Finally there are _\bt_\bz_\bh_\b__\bt_\bt_\bi_\bs_\bs_\bt_\bd_\bc_\bn_\bt standard/wall indicators, each stored as
    a one-byte value; they tell whether the transition times associated with
    local time types were specified as standard time or wall clock time, and
    are used when a time zone file is used in handling POSIX-style time zone
    environment variables.


    _\bL_\bo_\bc_\ba_\bl_\bt_\bi_\bm_\be uses the first standard-time _\bt_\bt_\bi_\bn_\bf_\bo structure in the file (or
    simply the first _\bt_\bt_\bi_\bn_\bf_\bo structure in the absence of a standard-time
    structure) if either _\bt_\bz_\bh_\b__\bt_\bi_\bm_\be_\bc_\bn_\bt is zero or the time argument is less
    than the first transition time recorded in the file.

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    ctime(3)

H\bHI\bIS\bST\bTO\bOR\bRY\bY
    The t\btz\bzf\bfi\bil\ble\be file format appeared in 4.3BSDtahoe.

4.4BSD                           June 8, 1993                                2