[Fri May 4 00:22:20 UTC 2018]

The 2018e release of the tz code and data is available. It reflects the 
following changes, which were either circulated on the tz mailing list 
or are relatively minor technical or administrative changes:

   Briefly:

     North Korea switches back to +09 on 2018-05-05.
     The main format uses negative DST again, for Ireland etc.
     'make tarballs' now also builds a rearguard tarball.
     New 's' and 'd' suffixes in SAVE columns of Rule and Zone lines.

   Changes to past and future time stamps

     North Korea switches back from +0830 to +09 on 2018-05-05.
     (Thanks to Kang Seonghoon, Arthur David Olson, Seo Sanghyeon,
     and Tim Parenti.)

     Bring back the negative-DST changes of 2018a, except be more
     compatible with data parsers that do not support negative DST.
     Also, this now affects historical time stamps in Namibia and the
     former Czechoslovakia, not just Ireland.  The main format now uses
     negative DST to model time stamps in Europe/Dublin (from 1971 on),
     Europe/Prague (1946/7), and Africa/Windhoek (1994/2017).  This
     does not affect UT offsets, only time zone abbreviations and the
     tm_isdst flag.  Also, this does not affect rearguard or vanguard
     formats; effectively the main format now uses vanguard instead of
     rearguard format.  Data parsers that do not support negative DST
     can still use data from the rearguard tarball described below.

   Changes to build procedure

     The command 'make tarballs' now also builds the tarball
     tzdataVERSION-rearguard.tar.gz, which is like tzdataVERSION.tar.gz
     except that it uses rearguard format intended for trailing-edge
     data parsers.

   Changes to data format and to code

     The SAVE column of Rule and Zone lines can now have an 's' or 'd'
     suffix, which specifies whether the adjusted time is standard time
     or daylight saving time.  If no suffix is given, daylight saving
     time is used if and only if the SAVE column is nonzero; this is
     the longstanding behavior.  Although this new feature is not used
     in tzdata, it could be used to specify the legal time in Namibia
     1994-2017, as opposed to the popular time (see below).

   Changes to past time stamps

     From 1994 through 2017 Namibia observed DST in winter, not summer.
     That is, it used negative DST, as Ireland still does.  This change
     does not affect UTC offsets; it affects only the tm_isdst flag and
     the abbreviation used during summer, which is now CAT, not WAST.
     Although (as noted by Michael Deckers) summer and winter time were
     both simply called "standard time" in Namibian law, in common
     practice winter time was considered to be DST (as noted by Stephen
     Colebourne).  The full effect of this change is only in vanguard
     format; in rearguard and main format, the tm_isdst flag is still
     zero in winter and nonzero in summer.

     In 1946/7 Czechoslovakia also observed negative DST in winter.
     The full effect of this change is only in vanguard format; in
     rearguard and main formats, it is modeled as plain GMT without
     daylight saving.  Also, the dates of some 1944/5 DST transitions
     in Czechoslovakia have been changed.

Here are links to the release files:

https://www.iana.org/time-zones/repository/releases/tzcode2018e.tar.gz
https://www.iana.org/time-zones/repository/releases/tzdata2018e.tar.gz
https://www.iana.org/time-zones/repository/releases/tzdb-2018e.tar.lz

Links are also available via plain HTTP, and via FTP from
ftp://ftp.iana.org/tz/releases with the same basenames as above.