contrib/tzcode/tzfile.5

250 Readers that understand only Version 1 must ignore
267 This guideline helps obsolescent version 1 readers
268 agree with current readers about timestamps within the
271 supporting obsolescent readers use a
277 time, TZif readers should either refuse to process
294 When reading a version 2 or higher file, readers
298 Readers should calculate the total lengths of the
302 When a positive leap second occurs, readers should append an extra
312 older readers.
317 pitfalls in older or buggy TZif readers,
319 TZif readers avoid common pitfalls when reading
333 newer-version data useful even for older-version readers.
336 readers.
341 Some readers examine only version 1 data.
348 Some readers designed for version 2 might mishandle
354 mishandled by version 2 readers.
356 Some readers might mishandle timestamps after a file's last transition,
364 Some readers designed for version 2 do not support
382 Some readers designed for version 2 or 3 and that require strict
386 Some readers ignore the footer, and instead predict future
391 Some stripped-down readers ignore everything but the footer,
403 Some readers do not use time type 0 for timestamps before
409 Some readers mishandle timestamps before the first
411 Readers that support only 32-bit timestamps are likely to be
418 Some readers mishandle a transition if its timestamp has
422 Some readers mishandle proleptic TZ strings that
434 Many readers mishandle time zone abbreviations that contain
438 Some readers may mishandle time zone abbreviations that
446 Some readers mishandle TZif files that specify
449 These readers do not support locations like Ireland, which
462 Some readers generate ambiguous timestamps for positive leap seconds
465 a positive leap second 78796801 (1972-06-30 23:59:60 UTC), some readers will
475 are listed here mostly as warnings to developers of readers.
478 Some readers do not support negative timestamps.
482 Some readers mishandle timestamps before the first
484 Readers that do not support negative timestamps are likely to
487 Some readers mishandle time zone abbreviations like
494 Some readers mishandle UT offsets that are out of the
499 Some readers mishandle UT offsets in the range [\-3599, \-1]
504 Some readers mishandle UT offsets that are not a multiple