| All ints and time_ts are 32 bits, big endian, packed on arbitrary byte boundaries | ||
|---|---|---|
| Type | Name | Use |
| char[4] | header | always "TZif" |
| char | version | '\0', '2' or '3' |
| char[15] | [future use] | all '\0' |
| int | tzh_ttisgmtcnt | count of UTC/local indicators |
| int | tzh_ttisstdcnt | count of standard/wall indicators |
| int | tzh_leapcnt | count of leap seconds |
| int | tzh_timecnt | count of transition times |
| int | tzh_typecnt | count of local time types (never zero) |
| int | tzh_charcnt | total characters in all abbreviation strings |
| time_t[tzh_timecnt] | – | transition times as returned by |
| unsigned char[tzh_timecnt] | indices into following ttinfo array | |
|
struct ttinfo { int tt_gmtoff; unsigned char tt_isdst; unsigned char tt_abbrind; } [tzh_typecnt] |
tt_gmtoff is total ISO 8601 offset (std + dst) tt_isdst is boolean indicating DST tt_abbrind is index to abbreviations |
|
| char[tzh_charcnt] | packed '\0'-terminated abbreviations | |
| time_t[tzh_leapcnt][2] |
[][0] is [][1] is count of leap seconds after |
|
| char[tzh_ttisstdcnt] | whether local transitions are standard or wall | |
| char[tzh_ttisgmtcnt] | whether local transitions are UTC or local | |
|
Version 2: additional copy of all the above, but with 64-bit time_ts (in yellow above), plus: |
||
| char[] | – |
|
|
Version 3 adds no data, but allows some extensions to the “POSIX TZ environment variable”. |
||