Import tzcode 2024b

CONTRIBUTING

@@ -23,10 +23,10 @@ such as renaming, adding or removing zones, please read
 "Theory and pragmatics of the tz code and data"
 <https://www.iana.org/time-zones/repository/theory.html>.
 It is also good to browse the mailing list archives
-<https://mm.icann.org/pipermail/tz/> for examples of patches that tend
+<https://lists.iana.org/hyperkitty/list/tz@iana.org/>
-to work well.  Additions to data should contain commentary citing
+for examples of patches that tend to work well.
-reliable sources as justification.  Citations should use "https:" URLs
+Changes should contain commentary citing reliable sources.
-if available.
+Citations should use "https:" URLs if available.
 
 For changes that fix sensitive security-related bugs, please see the
 distribution's 'SECURITY' file.
@@ -63,12 +63,16 @@ If you use Git the following workflow may be helpful:
   * Edit source files.  Include commentary that justifies the
     changes by citing reliable sources.
 
-  * Debug the changes, e.g.:
+  * Debug the changes locally, e.g.:
 
-        make check
+        make TOPDIR=$PWD/tz clean check install
-        make install
         ./zdump -v America/Los_Angeles
 
+    Although builds assume only basic POSIX, they use extra features
+    if available.  'make check' accesses validator.w3.org unless you
+    lack 'curl' or use 'make CURL=:'.  If you have the latest GCC,
+    "make CFLAGS='$(GCC_DEBUG_FLAGS)'" does extra checking.
+
   * For each separable change, commit it in the new branch, e.g.:
 
         git add northamerica

Makefile

@@ -3,17 +3,17 @@
 # 2009-05-17 by Arthur David Olson.
 # Request POSIX conformance; this must be the first non-comment line.
 .POSIX:
-# On older platforms you may need to scrounge for a POSIX-conforming 'make'.
+# On older platforms you may need to scrounge for POSIX conformance.
-# For example, on Solaris 10 (2005), use /usr/sfw/bin/gmake or
+# For example, on Solaris 10 (2005) with Sun Studio 12 aka Sun C 5.9 (2007),
-# /usr/xpg4/bin/make, not /usr/ccs/bin/make.
+# use 'PATH=/usr/xpg4/bin:$PATH make CC=c99'.
 
 # To affect how this Makefile works, you can run a shell script like this:
 #
 #	#!/bin/sh
-#	make CC='gcc -std=gnu11' "$@"
+#	make CC='gcc -std=gnu23' "$@"
 #
-# This example script is appropriate for a pre-2017 GNU/Linux system
+# This example script is appropriate for a circa 2024 GNU/Linux system
-# where a non-default setting is needed to support this package's use of C99.
+# where a non-default setting enables this package's optional use of C23.
 #
 # Alternatively, you can simply edit this Makefile to tailor the following
 # macro definitions.
@@ -53,7 +53,7 @@ DATAFORM=		main
 
 LOCALTIME=	Factory
 
-# The POSIXRULES macro controls interpretation of POSIX-2017.1-like TZ
+# The POSIXRULES macro controls interpretation of POSIX-like TZ
 # settings like TZ='EET-2EEST' that lack DST transition rules.
 # If POSIXRULES is '-', no template is installed; this is the default.
 # Any other value for POSIXRULES is obsolete and should not be relied on, as:
@@ -132,8 +132,9 @@ LIBDIR = $(TOPDIR)/$(USRDIR)/lib
 
 # Types to try, as an alternative to time_t.
 TIME_T_ALTERNATIVES = $(TIME_T_ALTERNATIVES_HEAD) $(TIME_T_ALTERNATIVES_TAIL)
-TIME_T_ALTERNATIVES_HEAD = int_least64_t
+TIME_T_ALTERNATIVES_HEAD = int_least64_t.ck
-TIME_T_ALTERNATIVES_TAIL = int_least32_t uint_least32_t uint_least64_t
+TIME_T_ALTERNATIVES_TAIL = int_least32_t.ck uint_least32_t.ck \
+  uint_least64_t.ck
 
 # What kind of TZif data files to generate.  (TZif is the binary time
 # zone data format that zic generates; see Internet RFC 8536.)
@@ -219,6 +220,7 @@ LDLIBS=
 #	than what POSIX specifies, assuming local time is UT.
 #	For example, N is 252460800 on AmigaOS.
 #  -DHAVE_DECL_ASCTIME_R=0 if <time.h> does not declare asctime_r
+#	on POSIX platforms predating POSIX.1-2024
 #  -DHAVE_DECL_ENVIRON if <unistd.h> declares 'environ'
 #  -DHAVE_DECL_TIMEGM=0 if <time.h> does not declare timegm
 #  -DHAVE_DIRECT_H if mkdir needs <direct.h> (MS-Windows)
@@ -229,7 +231,7 @@ LDLIBS=
 #	where LDLIBS also needs to contain -lintl on some hosts;
 #	-DHAVE_GETTEXT=0 to avoid using gettext
 #  -DHAVE_INCOMPATIBLE_CTIME_R if your system's time.h declares
-#	ctime_r and asctime_r incompatibly with the POSIX standard
+#	ctime_r and asctime_r incompatibly with POSIX.1-2017 and earlier
 #	(Solaris when _POSIX_PTHREAD_SEMANTICS is not defined).
 #  -DHAVE_INTTYPES_H=0 if <inttypes.h> does not work*+
 #  -DHAVE_LINK=0 if your system lacks a link function
@@ -261,8 +263,11 @@ LDLIBS=
 #  -DRESERVE_STD_EXT_IDS if your platform reserves standard identifiers
 #	with external linkage, e.g., applications cannot define 'localtime'.
 #  -Dssize_t=long on hosts like MS-Windows that lack ssize_t
-#  -DSUPPORT_C89 if the tzcode library should support C89 callers+
+#  -DSUPPORT_C89=0 if the tzcode library should not support C89 callers
-#	However, this might trigger latent bugs in C99-or-later callers.
+#	Although -DSUPPORT_C89=0 might work around latent bugs in callers,
+#	it does not conform to POSIX.
+#  -DSUPPORT_POSIX2008 if the library should support older POSIX callers+
+#	However, this might cause problems in POSIX.1-2024-or-later callers.
 #  -DSUPPRESS_TZDIR to not prepend TZDIR to file names; this has
 #	security implications and is not recommended for general use
 #  -DTHREAD_SAFE to make localtime.c thread-safe, as POSIX requires;
@@ -274,7 +279,7 @@ LDLIBS=
 #  -DTZ_DOMAINDIR=\"/path\" to use "/path" for gettext directory;
 #	the default is system-supplied, typically "/usr/lib/locale"
 #  -DTZDEFRULESTRING=\",date/time,date/time\" to default to the specified
-#	DST transitions for POSIX.1-2017-style TZ strings lacking them,
+#	DST transitions for proleptic format TZ strings lacking them,
 #	in the usual case where POSIXRULES is '-'.  If not specified,
 #	TZDEFRULESTRING defaults to US rules for future DST transitions.
 #	This mishandles some past timestamps, as US DST rules have changed.
@@ -302,23 +307,25 @@ LDLIBS=
 #
 # * Options marked "*" can be omitted if your compiler is C23 compatible.
 # * Options marked "+" are obsolescent and are planned to be removed
-#   once the code assumes C99 or later, say in the year 2029.
+#   once the code assumes C99 or later (say in the year 2029)
+#   and POSIX.1-2024 or later (say in the year 2034).
 #
 # Select instrumentation via "make GCC_INSTRUMENT='whatever'".
 GCC_INSTRUMENT = \
   -fsanitize=undefined -fsanitize-address-use-after-scope \
   -fsanitize-undefined-trap-on-error -fstack-protector
 # Omit -fanalyzer from GCC_DEBUG_FLAGS, as it makes GCC too slow.
-GCC_DEBUG_FLAGS = -DGCC_LINT -g3 -O3 -fno-common \
+GCC_DEBUG_FLAGS = -DGCC_LINT -g3 -O3 \
   $(GCC_INSTRUMENT) \
   -Wall -Wextra \
   -Walloc-size-larger-than=100000 -Warray-bounds=2 \
   -Wbad-function-cast -Wbidi-chars=any,ucn -Wcast-align=strict -Wdate-time \
   -Wdeclaration-after-statement -Wdouble-promotion \
-  -Wduplicated-branches -Wduplicated-cond \
+  -Wduplicated-branches -Wduplicated-cond -Wflex-array-member-not-at-end \
   -Wformat=2 -Wformat-overflow=2 -Wformat-signedness -Wformat-truncation \
   -Wimplicit-fallthrough=5 -Winit-self -Wlogical-op \
-  -Wmissing-declarations -Wmissing-prototypes -Wnested-externs \
+  -Wmissing-declarations -Wmissing-prototypes \
+  -Wmissing-variable-declarations -Wnested-externs \
   -Wnull-dereference \
   -Wold-style-definition -Woverlength-strings -Wpointer-arith \
   -Wshadow -Wshift-overflow=2 -Wstrict-overflow \
@@ -327,10 +334,9 @@ GCC_DEBUG_FLAGS = -DGCC_LINT -g3 -O3 -fno-common \
   -Wsuggest-attribute=const -Wsuggest-attribute=format \
   -Wsuggest-attribute=malloc \
   -Wsuggest-attribute=noreturn -Wsuggest-attribute=pure \
-  -Wtrampolines -Wundef -Wuninitialized -Wunused-macros -Wuse-after-free=3 \
+  -Wtrampolines -Wundef -Wunused-macros -Wuse-after-free=3 \
   -Wvariadic-macros -Wvla -Wwrite-strings \
-  -Wno-address -Wno-format-nonliteral -Wno-sign-compare \
+  -Wno-format-nonliteral -Wno-sign-compare
-  -Wno-type-limits
 #
 # If your system has a "GMT offset" field in its "struct tm"s
 # (or if you decide to add such a field in your system's "time.h" file),
@@ -341,9 +347,8 @@ GCC_DEBUG_FLAGS = -DGCC_LINT -g3 -O3 -fno-common \
 # Similarly, if your system has a "zone abbreviation" field, define
 #	-DTM_ZONE=tm_zone
 # and define NO_TM_ZONE to suppress any guessing.
-# Although these two fields are not required by POSIX.1-2017,
+# Although POSIX.1-2024 requires these fields and they are widely available
-# POSIX 202x/D4 requires them and they are widely available
+# on GNU/Linux and BSD systems, some older systems lack them.
-# on GNU/Linux and BSD systems.
 #
 # The next batch of options control support for external variables
 # exported by tzcode.  In practice these variables are less useful
@@ -353,7 +358,9 @@ GCC_DEBUG_FLAGS = -DGCC_LINT -g3 -O3 -fno-common \
 # #	-DHAVE_TZNAME=0 # do not support "tzname"
 # #	-DHAVE_TZNAME=1 # support "tzname", which is defined by system library
 # #	-DHAVE_TZNAME=2 # support and define "tzname"
-# # to the "CFLAGS=" line.  "tzname" is required by POSIX.1-1988 and later.
+# # to the "CFLAGS=" line.  Although "tzname" is required by POSIX.1-1988
+# # and later, its contents are unspecified if you use a geographical TZ
+# # and the variable is planned to be removed in a future POSIX edition.
 # # If not defined, the code attempts to guess HAVE_TZNAME from other macros.
 # # Warning: unless time_tz is also defined, HAVE_TZNAME=1 can cause
 # # crashes when combined with some platforms' standard libraries,
@@ -364,7 +371,9 @@ GCC_DEBUG_FLAGS = -DGCC_LINT -g3 -O3 -fno-common \
 # #	-DUSG_COMPAT=1 # support, and variables are defined by system library
 # #	-DUSG_COMPAT=2 # support and define variables
 # # to the "CFLAGS=" line; "timezone" and "daylight" are inspired by Unix
-# # Systems Group code and are required by POSIX.1-2008 and later (with XSI).
+# # Systems Group code and are required by POSIX.1-2008 and later (with XSI),
+# # although their contents are unspecified if you use a geographical TZ
+# # and the variables are planned to be removed in a future edition of POSIX.
 # # If not defined, the code attempts to guess USG_COMPAT from other macros.
 # #
 # # To support the external variable "altzone", add
@@ -428,18 +437,13 @@ GCC_DEBUG_FLAGS = -DGCC_LINT -g3 -O3 -fno-common \
 
 # The name of a POSIX-like library archiver, its flags, C compiler,
 # linker flags, and 'make' utility.  Ordinarily the defaults suffice.
-# The commented-out values are the defaults specified by POSIX.1-202x/D4.
+# The commented-out values are the defaults specified by POSIX.1-2024.
 #AR = ar
 #ARFLAGS = -rv
 #CC = c17
 #LDFLAGS =
 #MAKE = make
 
-# For leap seconds, this Makefile uses LEAPSECONDS='-L leapseconds' in
-# submake command lines.  The default is no leap seconds.
-
-LEAPSECONDS=
-
 # Where to fetch leap-seconds.list from.
 leaplist_URI = \
   https://hpiers.obspm.fr/iers/bul/bulc/ntp/leap-seconds.list
@@ -461,7 +465,7 @@ ZFLAGS=
 
 # How to use zic to install TZif files.
 
-ZIC_INSTALL=	$(ZIC) -d '$(DESTDIR)$(TZDIR)' $(LEAPSECONDS)
+ZIC_INSTALL=	$(ZIC) -d '$(DESTDIR)$(TZDIR)'
 
 # The name of a POSIX-compliant 'awk' on your system.
 # mawk 1.3.3 and Solaris 10 /usr/bin/awk do not work.
@@ -480,6 +484,7 @@ KSHELL=		/bin/bash
 
 # Name of curl <https://curl.haxx.se/>, used for HTML validation
 # and to fetch leap-seconds.list from upstream.
+# Set CURL=: to disable use of the Internet.
 CURL=		curl
 
 # Name of GNU Privacy Guard <https://gnupg.org/>, used to sign distributions.
@@ -533,21 +538,28 @@ OK_LINE=	'^'$(OK_CHAR)'*$$'
 
 # Flags to give 'tar' when making a distribution.
 # Try to use flags appropriate for GNU tar.
-GNUTARFLAGS= --format=pax --pax-option='delete=atime,delete=ctime' \
+GNUTARFLAGS= --format=pax --pax-option=delete=atime,delete=ctime \
   --numeric-owner --owner=0 --group=0 \
   --mode=go+u,go-w --sort=name
-TARFLAGS=	`if tar $(GNUTARFLAGS) --version >/dev/null 2>&1; \
+SETUP_TAR= \
-		 then echo $(GNUTARFLAGS); \
+  export LC_ALL=C && \
-		 else :; \
+  if tar $(GNUTARFLAGS) --version >/dev/null 2>&1; then \
-		 fi`
+    TAR='tar $(GNUTARFLAGS)'; \
+  else \
+    TAR=tar; \
+  fi
 
 # Flags to give 'gzip' when making a distribution.
 GZIPFLAGS=	-9n
 
 # When comparing .tzs files, use GNU diff's -F'^TZ=' option if supported.
 # This makes it easier to see which Zone has been affected.
-DIFF_TZS=	 diff -u$$(! diff -u -F'^TZ=' - - <>/dev/null >&0 2>&1 \
+SETUP_DIFF_TZS = \
-			   || echo ' -F^TZ=')
+  if diff -u -F'^TZ=' - - <>/dev/null >&0 2>&1; then \
+    DIFF_TZS='diff -u -F^TZ='; \
+  else \
+    DIFF_TZS='diff -u'; \
+  fi
 
 # ':' on typical hosts; 'ranlib' on the ancient hosts that still need ranlib.
 RANLIB=		:
@@ -561,8 +573,8 @@ RANLIB=		:
 
 
 TZCOBJS=	zic.o
-TZDOBJS=	zdump.o localtime.o asctime.o strftime.o
+TZDOBJS=	zdump.o localtime.o strftime.o
-DATEOBJS=	date.o localtime.o strftime.o asctime.o
+DATEOBJS=	date.o localtime.o strftime.o
 LIBSRCS=	localtime.c asctime.c difftime.c strftime.c
 LIBOBJS=	localtime.o asctime.o difftime.o strftime.o
 HEADERS=	tzfile.h private.h
@@ -579,8 +591,7 @@ MANTXTS=	newctime.3.txt newstrftime.3.txt newtzset.3.txt \
 COMMON=		calendars CONTRIBUTING LICENSE Makefile \
 			NEWS README SECURITY theory.html version
 WEB_PAGES=	tz-art.html tz-how-to.html tz-link.html
-CHECK_WEB_PAGES=check_theory.html check_tz-art.html \
+CHECK_WEB_PAGES=theory.ck tz-art.ck tz-how-to.ck tz-link.ck
-			check_tz-how-to.html check_tz-link.html
 DOCS=		$(MANS) date.1 $(MANTXTS) $(WEB_PAGES)
 PRIMARY_YDATA=	africa antarctica asia australasia \
 		europe northamerica southamerica
@@ -641,8 +652,7 @@ install:	all $(DATA) $(REDO) $(MANS)
 			'$(DESTDIR)$(MANDIR)/man3' '$(DESTDIR)$(MANDIR)/man5' \
 			'$(DESTDIR)$(MANDIR)/man8'
 		$(ZIC_INSTALL) -l $(LOCALTIME) \
-			`case '$(POSIXRULES)' in ?*) echo '-p';; esac \
+			-p $(POSIXRULES) \
-			` $(POSIXRULES) \
 			-t '$(DESTDIR)$(TZDEFAULT)'
 		cp -f $(TABDATA) '$(DESTDIR)$(TZDIR)/.'
 		cp tzselect '$(DESTDIR)$(BINDIR)/.'
@@ -665,10 +675,10 @@ INSTALL:	ALL install date.1
 # and append "-dirty" if the contents do not already end in "-dirty".
 version:	$(VERSION_DEPS)
 		{ (type git) >/dev/null 2>&1 && \
-		  V=`git describe --match '[0-9][0-9][0-9][0-9][a-z]*' \
+		  V=$$(git describe --match '[0-9][0-9][0-9][0-9][a-z]*' \
-				--abbrev=7 --dirty` || \
+				--abbrev=7 --dirty) || \
-		  if test '$(VERSION)' = unknown && V=`cat $@`; then \
+		  if test '$(VERSION)' = unknown && read -r V <$@; then \
-		    case $$V in *-dirty);; *) V=$$V-dirty;; esac; \
+		    V=$${V%-dirty}-dirty; \
 		  else \
 		    V='$(VERSION)'; \
 		  fi; } && \
@@ -678,7 +688,7 @@ version:	$(VERSION_DEPS)
 # These files can be tailored by setting BACKWARD, PACKRATDATA, PACKRATLIST.
 vanguard.zi main.zi rearguard.zi: $(DSTDATA_ZI_DEPS)
 		$(AWK) \
-		  -v DATAFORM=`expr $@ : '\(.*\).zi'` \
+		  -v DATAFORM=$(@:.zi=) \
 		  -v PACKRATDATA='$(PACKRATDATA)' \
 		  -v PACKRATLIST='$(PACKRATLIST)' \
 		  -f ziguard.awk \
@@ -687,7 +697,7 @@ vanguard.zi main.zi rearguard.zi: $(DSTDATA_ZI_DEPS)
 # This file has a version comment that attempts to capture any tailoring
 # via BACKWARD, DATAFORM, PACKRATDATA, PACKRATLIST, and REDO.
 tzdata.zi:	$(DATAFORM).zi version zishrink.awk
-		version=`sed 1q version` && \
+		read -r version <version && \
 		  LC_ALL=C $(AWK) \
 		    -v dataform='$(DATAFORM)' \
 		    -v deps='$(DSTDATA_ZI_DEPS) zishrink.awk' \
@@ -708,7 +718,7 @@ tzdir.h:
 		mv $@.out $@
 
 version.h:	version
-		VERSION=`cat version` && printf '%s\n' \
+		read -r VERSION <version && printf '%s\n' \
 		  'static char const PKGVERSION[]="($(PACKAGE)) ";' \
 		  "static char const TZVERSION[]=\"$$VERSION\";" \
 		  'static char const REPORT_BUGS_TO[]="$(BUGEMAIL)";' \
@@ -748,12 +758,11 @@ commit-leap-seconds.list: fetch-leap-seconds.list
 		git commit --author="$$author" --date="$$date" -m'make $@' \
 		  leap-seconds.list
 
-# Arguments to pass to submakes of install_data.
+# Arguments to pass to submakes.
 # They can be overridden by later submake arguments.
 INSTALLARGS = \
  BACKWARD='$(BACKWARD)' \
  DESTDIR='$(DESTDIR)' \
- LEAPSECONDS='$(LEAPSECONDS)' \
  PACKRATDATA='$(PACKRATDATA)' \
  PACKRATLIST='$(PACKRATLIST)' \
  TZDEFAULT='$(TZDEFAULT)' \
@@ -762,16 +771,11 @@ INSTALLARGS = \
 
 INSTALL_DATA_DEPS = zic leapseconds tzdata.zi
 
-# 'make install_data' installs one set of TZif files.
+posix_only: $(INSTALL_DATA_DEPS)
-install_data: $(INSTALL_DATA_DEPS)
 		$(ZIC_INSTALL) tzdata.zi
 
-posix_only: $(INSTALL_DATA_DEPS)
-		$(MAKE) $(INSTALLARGS) LEAPSECONDS= install_data
-
 right_only: $(INSTALL_DATA_DEPS)
-		$(MAKE) $(INSTALLARGS) LEAPSECONDS='-L leapseconds' \
+		$(ZIC_INSTALL) -L leapseconds tzdata.zi
-			install_data
 
 # In earlier versions of this makefile, the other two directories were
 # subdirectories of $(TZDIR).  However, this led to configuration errors.
@@ -802,8 +806,7 @@ ZDS = dummy.zd
 # Rule used only by submakes invoked by the $(TZS_NEW) rule.
 # It is separate so that GNU 'make -j' can run instances in parallel.
 $(ZDS): zdump
-		./zdump -i $(TZS_CUTOFF_FLAG) '$(wd)/'$$(expr $@ : '\(.*\).zd') \
+		./zdump -i $(TZS_CUTOFF_FLAG) "$$PWD/$(@:.zd=)" >$@
-		  >$@
 
 TZS_NEW_DEPS = tzdata.zi zdump zic
 $(TZS_NEW): $(TZS_NEW_DEPS)
@@ -812,20 +815,19 @@ $(TZS_NEW): $(TZS_NEW_DEPS)
 		$(zic) -d tzs$(TZS_YEAR).dir tzdata.zi
 		$(AWK) '/^L/{print "Link\t" $$2 "\t" $$3}' \
 		   tzdata.zi | LC_ALL=C sort >$@.out
-		wd=`pwd` && \
+		x=$$($(AWK) '/^Z/{print "tzs$(TZS_YEAR).dir/" $$2 ".zd"}' \
-		x=`$(AWK) '/^Z/{print "tzs$(TZS_YEAR).dir/" $$2 ".zd"}' \
 				tzdata.zi \
-			| LC_ALL=C sort -t . -k 2,2` && \
+		     | LC_ALL=C sort -t . -k 2,2) && \
 		set x $$x && \
 		shift && \
 		ZDS=$$* && \
-		$(MAKE) wd="$$wd" TZS_CUTOFF_FLAG="$(TZS_CUTOFF_FLAG)" \
+		$(MAKE) TZS_CUTOFF_FLAG="$(TZS_CUTOFF_FLAG)" \
 		  ZDS="$$ZDS" $$ZDS && \
 		sed 's,^TZ=".*\.dir/,TZ=",' $$ZDS >>$@.out
 		rm -fr tzs$(TZS_YEAR).dir
 		mv $@.out $@
 
-# If $(TZS) exists but 'make check_tzs' fails, a maintainer should inspect the
+# If $(TZS) exists but 'make tzs.ck' fails, a maintainer should inspect the
 # failed output and fix the inconsistency, perhaps by running 'make force_tzs'.
 $(TZS):
 		touch $@
@@ -842,7 +844,7 @@ date:		$(DATEOBJS)
 		$(CC) -o $@ $(CFLAGS) $(LDFLAGS) $(DATEOBJS) $(LDLIBS)
 
 tzselect:	tzselect.ksh version
-		VERSION=`cat version` && sed \
+		read -r VERSION <version && sed \
 		  -e "s'#!/bin/bash'#!"'$(KSHELL)'\' \
 		  -e s\''\(AWK\)=[^}]*'\''\1=\'\''$(AWK)\'\'\' \
 		  -e s\''\(PKGVERSION\)=.*'\''\1=\'\''($(PACKAGE)) \'\'\' \
@@ -853,11 +855,11 @@ tzselect:	tzselect.ksh version
 		chmod +x $@.out
 		mv $@.out $@
 
-check: check_back check_mild
+check: check_mild back.ck
-check_mild:	check_character_set check_white_space check_links \
+check_mild: check_web check_zishrink \
-		  check_name_lengths check_now \
+  character-set.ck white-space.ck links.ck mainguard.ck \
-		  check_slashed_abbrs check_sorted \
+  name-lengths.ck now.ck slashed-abbrs.ck sorted.ck \
-		  check_tables check_web check_ziguard check_zishrink check_tzs
+  tables.ck ziguard.ck tzs.ck
 
 # True if UTF8_LOCALE does not work;
 # otherwise, false but with LC_ALL set to $(UTF8_LOCALE).
@@ -865,9 +867,9 @@ UTF8_LOCALE_MISSING = \
   { test ! '$(UTF8_LOCALE)' \
     || ! printf 'A\304\200B\n' \
          | LC_ALL='$(UTF8_LOCALE)' grep -q '^A.B$$' >/dev/null 2>&1 \
-    || { LC_ALL='$(UTF8_LOCALE)'; export LC_ALL; false; }; }
+    || { export LC_ALL='$(UTF8_LOCALE)'; false; }; }
 
-check_character_set: $(ENCHILADA)
+character-set.ck: $(ENCHILADA)
 	$(UTF8_LOCALE_MISSING) || { \
 		sharp='#' && \
 		! grep -Env $(SAFE_LINE) $(MANS) date.1 $(MANTXTS) \
@@ -882,48 +884,55 @@ check_character_set: $(ENCHILADA)
 	}
 	touch $@
 
-check_white_space: $(ENCHILADA)
+white-space.ck: $(ENCHILADA)
 	$(UTF8_LOCALE_MISSING) || { \
-		patfmt=' \t|[\f\r\v]' && pat=`printf "$$patfmt\\n"` && \
+		enchilada='$(ENCHILADA)' && \
+		patfmt=' \t|[\f\r\v]' && pat=$$(printf "$$patfmt\\n") && \
 		! grep -En "$$pat|[$s]\$$" \
-			$$(ls $(ENCHILADA) | grep -Fvx leap-seconds.list); \
+		    $${enchilada%leap-seconds.list*} \
+		    $${enchilada#*leap-seconds.list}; \
 	}
 	touch $@
 
 PRECEDES_FILE_NAME = ^(Zone|Link[$s]+[^$s]+)[$s]+
 FILE_NAME_COMPONENT_TOO_LONG = $(PRECEDES_FILE_NAME)[^$s]*[^/$s]{15}
 
-check_name_lengths: $(TDATA_TO_CHECK) backzone
+name-lengths.ck: $(TDATA_TO_CHECK) backzone
-		! grep -En '$(FILE_NAME_COMPONENT_TOO_LONG)' \
+		:;! grep -En '$(FILE_NAME_COMPONENT_TOO_LONG)' \
 			$(TDATA_TO_CHECK) backzone
 		touch $@
 
+mainguard.ck: main.zi
+		test '$(PACKRATLIST)' || \
+		  cat $(TDATA) $(PACKRATDATA) | diff -u - main.zi
+		touch $@
+
 PRECEDES_STDOFF = ^(Zone[$s]+[^$s]+)?[$s]+
 STDOFF = [-+]?[0-9:.]+
 RULELESS_SAVE = (-|$(STDOFF)[sd]?)
 RULELESS_SLASHED_ABBRS = \
   $(PRECEDES_STDOFF)$(STDOFF)[$s]+$(RULELESS_SAVE)[$s]+[^$s]*/
 
-check_slashed_abbrs: $(TDATA_TO_CHECK)
+slashed-abbrs.ck: $(TDATA_TO_CHECK)
-		! grep -En '$(RULELESS_SLASHED_ABBRS)' $(TDATA_TO_CHECK)
+		:;! grep -En '$(RULELESS_SLASHED_ABBRS)' $(TDATA_TO_CHECK)
 		touch $@
 
 CHECK_CC_LIST = { n = split($$1,a,/,/); for (i=2; i<=n; i++) print a[1], a[i]; }
 
-check_sorted: backward backzone
+sorted.ck: backward backzone
 		$(AWK) '/^Link/ {printf "%.5d %s\n", g, $$3} !/./ {g++}' \
 		  backward | LC_ALL=C sort -cu
-		$(AWK) '/^Zone/ {print $$2}' backzone | LC_ALL=C sort -cu
+		$(AWK) '/^Zone.*\// {print $$2}' backzone | LC_ALL=C sort -cu
 		touch $@
 
-check_back:	checklinks.awk $(TDATA_TO_CHECK)
+back.ck: checklinks.awk $(TDATA_TO_CHECK)
 		$(AWK) \
 		  -v DATAFORM=$(DATAFORM) \
 		  -v backcheck=backward \
 		  -f checklinks.awk $(TDATA_TO_CHECK)
 		touch $@
 
-check_links:	checklinks.awk tzdata.zi
+links.ck: checklinks.awk tzdata.zi
 		$(AWK) \
 		  -v DATAFORM=$(DATAFORM) \
 		  -f checklinks.awk tzdata.zi
@@ -932,26 +941,36 @@ check_links:	checklinks.awk tzdata.zi
 # Check timestamps from now through 28 years from now, to make sure
 # that zonenow.tab contains all sequences of planned timestamps,
 # without any duplicate sequences.  In theory this might require
-# 2800 years but that would take a long time to check.
+# 2800+ years but that would take a long time to check.
-CHECK_NOW_TIMESTAMP = `./date +%s`
+CHECK_NOW_TIMESTAMP = $$(./date +%s)
 CHECK_NOW_FUTURE_YEARS = 28
-CHECK_NOW_FUTURE_SECS = $(CHECK_NOW_FUTURE_YEARS) '*' 366 '*' 24 '*' 60 '*' 60
+CHECK_NOW_FUTURE_SECS = $(CHECK_NOW_FUTURE_YEARS) * 366 * 24 * 60 * 60
-check_now:	checknow.awk date tzdata.zi zdump zic zone1970.tab zonenow.tab
+now.ck: checknow.awk date tzdata.zi zdump zic zone1970.tab zonenow.tab
-		rm -fr $@.dir
+		rm -fr $@d
-		mkdir $@.dir
+		mkdir $@d
-		./zic -d $@.dir tzdata.zi
+		./zic -d $@d tzdata.zi
 		now=$(CHECK_NOW_TIMESTAMP) && \
-		  future=`expr $(CHECK_NOW_FUTURE_SECS) + $$now` && \
+		  future=$$(($(CHECK_NOW_FUTURE_SECS) + $$now)) && \
 		  ./zdump -i -t $$now,$$future \
-		     $$(find $$PWD/$@.dir/????*/ -type f) \
+		     $$(find "$$PWD/$@d"/????*/ -type f) \
-		     >$@.dir/zdump.tab
+		     >$@d/zdump-now.tab && \
+		  ./zdump -i -t 0,$$future \
+		     $$(find "$$PWD/$@d" -name Etc -prune \
+			  -o -type f ! -name '*.tab' -print) \
+		     >$@d/zdump-1970.tab
 		$(AWK) \
-		  -v zdump_table=$@.dir/zdump.tab \
+		  -v zdump_table=$@d/zdump-now.tab \
 		  -f checknow.awk zonenow.tab
-		rm -fr $@.dir
+		$(AWK) \
+		  'BEGIN {print "-\t-\tUTC"} /^Zone/ {print "-\t-\t" $$2}' \
+		  $(PRIMARY_YDATA) backward factory | \
+		 $(AWK) \
+		   -v zdump_table=$@d/zdump-1970.tab \
+		   -f checknow.awk
+		rm -fr $@d
 		touch $@
 
-check_tables:	checktab.awk $(YDATA) backward zone.tab zone1970.tab
+tables.ck: checktab.awk $(YDATA) backward zone.tab zone1970.tab
 		for tab in $(ZONETABLES); do \
 		  test "$$tab" = zone.tab && links='$(BACKWARD)' || links=''; \
 		  $(AWK) -f checktab.awk -v zone_table=$$tab $(YDATA) $$links \
@@ -959,26 +978,24 @@ check_tables:	checktab.awk $(YDATA) backward zone.tab zone1970.tab
 		done
 		touch $@
 
-check_tzs:	$(TZS) $(TZS_NEW)
+tzs.ck: $(TZS) $(TZS_NEW)
 		if test -s $(TZS); then \
-		  $(DIFF_TZS) $(TZS) $(TZS_NEW); \
+		  $(SETUP_DIFF_TZS) && $$DIFF_TZS $(TZS) $(TZS_NEW); \
 		else \
 		  cp $(TZS_NEW) $(TZS); \
 		fi
 		touch $@
 
 check_web:	$(CHECK_WEB_PAGES)
-check_theory.html: theory.html
+.SUFFIXES: .ck .html
-check_tz-art.html: tz-art.html
+.html.ck:
-check_tz-how-to.html: tz-how-to.html
+		{ ! ($(CURL) --version) >/dev/null 2>&1 || \
-check_tz-link.html: tz-link.html
+		    $(CURL) -sS --url https://validator.w3.org/nu/ -F out=gnu \
-check_theory.html check_tz-art.html check_tz-how-to.html check_tz-link.html:
+		          -F file=@$<; } >$@.out && \
-		$(CURL) -sS --url https://validator.w3.org/nu/ -F out=gnu \
-		    -F file=@$$(expr $@ : 'check_\(.*\)') -o $@.out && \
 		  test ! -s $@.out || { cat $@.out; exit 1; }
 		mv $@.out $@
 
-check_ziguard: rearguard.zi vanguard.zi ziguard.awk
+ziguard.ck: rearguard.zi vanguard.zi ziguard.awk
 		$(AWK) -v DATAFORM=rearguard -f ziguard.awk vanguard.zi | \
 		  diff -u rearguard.zi -
 		$(AWK) -v DATAFORM=vanguard -f ziguard.awk rearguard.zi | \
@@ -987,36 +1004,35 @@ check_ziguard: rearguard.zi vanguard.zi ziguard.awk
 
 # Check that zishrink.awk does not alter the data, and that ziguard.awk
 # preserves main-format data.
-check_zishrink: check_zishrink_posix check_zishrink_right
+check_zishrink: zishrink-posix.ck zishrink-right.ck
-check_zishrink_posix check_zishrink_right: \
+zishrink-posix.ck zishrink-right.ck: \
   zic leapseconds $(PACKRATDATA) $(PACKRATLIST) \
   $(TDATA) $(DATAFORM).zi tzdata.zi
-		rm -fr $@.dir $@-t.dir $@-shrunk.dir
+		rm -fr $@d t-$@d shrunk-$@d
-		mkdir $@.dir $@-t.dir $@-shrunk.dir
+		mkdir $@d t-$@d shrunk-$@d
 		case $@ in \
-		  *_right) leap='-L leapseconds';; \
+		  *right*) leap='-L leapseconds';; \
 		  *) leap=;; \
 		esac && \
-		  $(ZIC) $$leap -d $@.dir $(DATAFORM).zi && \
+		  $(ZIC) $$leap -d $@d $(DATAFORM).zi && \
-		  $(ZIC) $$leap -d $@-shrunk.dir tzdata.zi && \
+		  $(ZIC) $$leap -d shrunk-$@d tzdata.zi && \
 		  case $(DATAFORM),$(PACKRATLIST) in \
 		    main,) \
-		      $(ZIC) $$leap -d $@-t.dir $(TDATA) && \
+		      $(ZIC) $$leap -d t-$@d $(TDATA) && \
 		      $(AWK) '/^Rule/' $(TDATA) | \
-			$(ZIC) $$leap -d $@-t.dir - $(PACKRATDATA) && \
+			$(ZIC) $$leap -d t-$@d - $(PACKRATDATA) && \
-		      diff -r $@.dir $@-t.dir;; \
+		      diff -r $@d t-$@d;; \
 		  esac
-		diff -r $@.dir $@-shrunk.dir
+		diff -r $@d shrunk-$@d
-		rm -fr $@.dir $@-t.dir $@-shrunk.dir
+		rm -fr $@d t-$@d shrunk-$@d
 		touch $@
 
 clean_misc:
-		rm -fr check_*.dir typecheck_*.dir
+		rm -fr *.ckd *.dir
-		rm -f *.o *.out $(TIME_T_ALTERNATIVES) \
+		rm -f *.ck *.core *.o *.out core core.* \
-		  check_* core typecheck_* \
 		  date tzdir.h tzselect version.h zdump zic libtz.a
 clean:		clean_misc
-		rm -fr *.dir tzdb-*/
+		rm -fr tzdb-*/
 		rm -f *.zi $(TZS_NEW)
 
 maintainer-clean: clean
@@ -1027,7 +1043,7 @@ maintainer-clean: clean
 names:
 		@echo $(ENCHILADA)
 
-public:		check check_public $(CHECK_TIME_T_ALTERNATIVES) \
+public: check public.ck $(CHECK_TIME_T_ALTERNATIVES) \
 		tarballs signatures
 
 date.1.txt:	date.1
@@ -1041,7 +1057,7 @@ zdump.8.txt:	zdump.8
 zic.8.txt:	zic.8
 
 $(MANTXTS):	workman.sh
-		LC_ALL=C sh workman.sh `expr $@ : '\(.*\)\.txt$$'` >$@.out
+		LC_ALL=C sh workman.sh $(@:.txt=) >$@.out
 		mv $@.out $@
 
 # Set file timestamps deterministically if possible,
@@ -1054,13 +1070,13 @@ SET_TIMESTAMP_N = sh -c '\
   n=$$0 dest=$$1; shift; \
   <"$$dest" && \
   if test $$n != 0 && \
-     lsout=`ls -nt --time-style="+%s" "$$@" 2>/dev/null`; then \
+     lsout=$$(ls -nt --time-style="+%s" "$$@" 2>/dev/null); then \
     set x $$lsout && \
-    timestamp=`expr $$7 + $$n` && \
+    timestamp=$$(($$7 + $$n)) && \
     echo "+ touch -md @$$timestamp $$dest" && \
     touch -md @$$timestamp "$$dest"; \
   else \
-    newest=`ls -t "$$@" | sed 1q` && \
+    newest=$$(ls -t "$$@" | sed 1q) && \
     echo "+ touch -mr $$newest $$dest" && \
     touch -mr "$$newest" "$$dest"; \
   fi'
@@ -1083,15 +1099,15 @@ SET_TIMESTAMP_DEP = $(SET_TIMESTAMP_N) 1
 set-timestamps.out: $(EIGHT_YARDS)
 		rm -f $@
 		if (type git) >/dev/null 2>&1 && \
-		   files=`git ls-files $(EIGHT_YARDS)` && \
+		   files=$$(git ls-files $(EIGHT_YARDS)) && \
 		   touch -md @1 test.out; then \
 		  rm -f test.out && \
 		  for file in $$files; do \
 		    if git diff --quiet $$file; then \
-		      time=`TZ=UTC0 git log -1 \
+		      time=$$(TZ=UTC0 git log -1 \
 			--format='tformat:%cd' \
 			--date='format:%Y-%m-%dT%H:%M:%SZ' \
-			$$file` && \
+			$$file) && \
 		      echo "+ touch -md $$time $$file" && \
 		      touch -md $$time $$file; \
 		    else \
@@ -1100,8 +1116,8 @@ set-timestamps.out: $(EIGHT_YARDS)
 		  done; \
 		fi
 		$(SET_TIMESTAMP_DEP) leapseconds $(LEAP_DEPS)
-		for file in `ls $(MANTXTS) | sed 's/\.txt$$//'`; do \
+		for file in $(MANTXTS); do \
-		  $(SET_TIMESTAMP_DEP) $$file.txt $$file workman.sh || \
+		  $(SET_TIMESTAMP_DEP) $$file $${file%.txt} workman.sh || \
 		    exit; \
 		done
 		$(SET_TIMESTAMP_DEP) version $(VERSION_DEPS)
@@ -1114,30 +1130,29 @@ set-tzs-timestamp.out: $(TZS)
 # The zics below ensure that each data file can stand on its own.
 # We also do an all-files run to catch links to links.
 
-check_public: $(VERSION_DEPS)
+public.ck: $(VERSION_DEPS)
-		rm -fr public.dir
+		rm -fr $@d
-		mkdir public.dir
+		mkdir $@d
-		ln $(VERSION_DEPS) public.dir
+		ln $(VERSION_DEPS) $@d
-		cd public.dir \
+		cd $@d \
 		  && $(MAKE) CFLAGS='$(GCC_DEBUG_FLAGS)' TZDIR='$(TZDIR)' ALL
-		for i in $(TDATA_TO_CHECK) public.dir/tzdata.zi \
+		for i in $(TDATA_TO_CHECK) \
-		    public.dir/vanguard.zi public.dir/main.zi \
+		    tzdata.zi vanguard.zi main.zi rearguard.zi; \
-		    public.dir/rearguard.zi; \
 		do \
-		  public.dir/zic -v -d public.dir/zoneinfo $$i 2>&1 || exit; \
+		  $@d/zic -v -d $@d/zoneinfo $@d/$$i || exit; \
 		done
-		public.dir/zic -v -d public.dir/zoneinfo-all $(TDATA_TO_CHECK)
+		$@d/zic -v -d $@d/zoneinfo-all $(TDATA_TO_CHECK)
 		:
 		: Also check 'backzone' syntax.
-		rm public.dir/main.zi
+		rm $@d/main.zi
-		cd public.dir && $(MAKE) PACKRATDATA=backzone main.zi
+		cd $@d && $(MAKE) PACKRATDATA=backzone main.zi
-		public.dir/zic -d public.dir/zoneinfo main.zi
+		$@d/zic -d $@d/zoneinfo main.zi
-		rm public.dir/main.zi
+		rm $@d/main.zi
-		cd public.dir && \
+		cd $@d && \
 		  $(MAKE) PACKRATDATA=backzone PACKRATLIST=zone.tab main.zi
-		public.dir/zic -d public.dir/zoneinfo main.zi
+		$@d/zic -d $@d/zoneinfo main.zi
 		:
-		rm -fr public.dir
+		rm -fr $@d
 		touch $@
 
 # Check that the code works under various alternative
@@ -1145,46 +1160,47 @@ check_public: $(VERSION_DEPS)
 check_time_t_alternatives: $(TIME_T_ALTERNATIVES)
 $(TIME_T_ALTERNATIVES_TAIL): $(TIME_T_ALTERNATIVES_HEAD)
 $(TIME_T_ALTERNATIVES): $(VERSION_DEPS)
-		rm -fr $@.dir
+		rm -fr $@d
-		mkdir $@.dir
+		mkdir $@d
-		ln $(VERSION_DEPS) $@.dir
+		ln $(VERSION_DEPS) $@d
 		case $@ in \
-		  int*32_t) range=-2147483648,2147483648;; \
+		  *32_t*) range=-2147483648,2147483648;; \
 		  u*) range=0,4294967296;; \
 		  *) range=-4294967296,4294967296;; \
 		esac && \
-		wd=`pwd` && \
+		wd=$$PWD && \
-		zones=`$(AWK) '/^[^#]/ { print $$3 }' <zone1970.tab` && \
+		zones=$$($(AWK) '/^[^#]/ { print $$3 }' <zone1970.tab) && \
 		if test $@ = $(TIME_T_ALTERNATIVES_HEAD); then \
 		  range_target=; \
 		else \
 		  range_target=to$$range.tzs; \
 		fi && \
-		(cd $@.dir && \
+		(cd $@d && \
-		  $(MAKE) TOPDIR="$$wd/$@.dir" \
+		  $(MAKE) TOPDIR="$$wd/$@d" \
-		    CFLAGS='$(CFLAGS) -Dtime_tz='"'$@'" \
+		    CFLAGS='$(CFLAGS) -Dtime_tz='"'$(@:.ck=)'" \
 		    REDO='$(REDO)' \
-			D=$$wd/$@.dir \
+		    D="$$wd/$@d" \
 		    TZS_YEAR="$$range" TZS_CUTOFF_FLAG="-t $$range" \
 		    install $$range_target) && \
 		test $@ = $(TIME_T_ALTERNATIVES_HEAD) || { \
-		  (cd $(TIME_T_ALTERNATIVES_HEAD).dir && \
+		  (cd $(TIME_T_ALTERNATIVES_HEAD)d && \
-		    $(MAKE) TOPDIR="$$wd/$@.dir" \
+		    $(MAKE) TOPDIR="$$wd/$@d" \
 		      TZS_YEAR="$$range" TZS_CUTOFF_FLAG="-t $$range" \
-			D=$$wd/$@.dir \
+		      D="$$wd/$@d" \
 		      to$$range.tzs) && \
-		  $(DIFF_TZS) $(TIME_T_ALTERNATIVES_HEAD).dir/to$$range.tzs \
+		  $(SETUP_DIFF_TZS) && \
-			  $@.dir/to$$range.tzs && \
+		  $$DIFF_TZS $(TIME_T_ALTERNATIVES_HEAD)d/to$$range.tzs \
+			  $@d/to$$range.tzs && \
 		  if diff -q Makefile Makefile 2>/dev/null; then \
 		    quiet_option='-q'; \
 		  else \
 		    quiet_option=''; \
 		  fi && \
-		    diff $$quiet_option -r $(TIME_T_ALTERNATIVES_HEAD).dir/etc \
+		    diff $$quiet_option -r $(TIME_T_ALTERNATIVES_HEAD)d/etc \
-					   $@.dir/etc && \
+					   $@d/etc && \
 		    diff $$quiet_option -r \
-		      $(TIME_T_ALTERNATIVES_HEAD).dir/usr/share \
+		      $(TIME_T_ALTERNATIVES_HEAD)d/usr/share \
-		      $@.dir/usr/share; \
+		      $@d/usr/share; \
 		}
 		touch $@
 
@@ -1199,7 +1215,7 @@ ALL_ASC = $(TRADITIONAL_ASC) $(REARGUARD_ASC) \
 tarballs rearguard_tarballs tailored_tarballs traditional_tarballs \
 signatures rearguard_signatures traditional_signatures: \
   version set-timestamps.out rearguard.zi vanguard.zi
-		VERSION=`cat version` && \
+		read -r VERSION <version && \
 		$(MAKE) AWK='$(AWK)' VERSION="$$VERSION" $@_version
 
 # These *_version rules are intended for use if VERSION is set by some
@@ -1218,15 +1234,15 @@ rearguard_signatures_version: $(REARGUARD_ASC)
 traditional_signatures_version: $(TRADITIONAL_ASC)
 
 tzcode$(VERSION).tar.gz: set-timestamps.out
-		LC_ALL=C && export LC_ALL && \
+		$(SETUP_TAR) && \
-		tar $(TARFLAGS) -cf - \
+		$$TAR -cf - \
 		    $(COMMON) $(DOCS) $(SOURCES) | \
 		  gzip $(GZIPFLAGS) >$@.out
 		mv $@.out $@
 
 tzdata$(VERSION).tar.gz: set-timestamps.out
-		LC_ALL=C && export LC_ALL && \
+		$(SETUP_TAR) && \
-		tar $(TARFLAGS) -cf - $(TZDATA_DIST) | \
+		$$TAR -cf - $(TZDATA_DIST) | \
 		  gzip $(GZIPFLAGS) >$@.out
 		mv $@.out $@
 
@@ -1251,9 +1267,9 @@ tzdata$(VERSION)-rearguard.tar.gz: rearguard.zi set-timestamps.out
 		: The dummy pacificnew pacifies TZUpdater 2.3.1 and earlier.
 		$(CREATE_EMPTY) $@.dir/pacificnew
 		touch -mr version $@.dir/version
-		LC_ALL=C && export LC_ALL && \
+		$(SETUP_TAR) && \
 		  (cd $@.dir && \
-		   tar $(TARFLAGS) -cf - \
+		   $$TAR -cf - \
 			$(TZDATA_DIST) pacificnew | \
 		     gzip $(GZIPFLAGS)) >$@.out
 		mv $@.out $@
@@ -1269,9 +1285,14 @@ tzdata$(VERSION)-tailored.tar.gz: set-timestamps.out
 		rm -fr $@.dir
 		mkdir $@.dir
 		: The dummy pacificnew pacifies TZUpdater 2.3.1 and earlier.
+		if test $(DATAFORM) = vanguard; then \
+		  pacificnew=; \
+		else \
+		  pacificnew=pacificnew; \
+		fi && \
 		cd $@.dir && \
 		  $(CREATE_EMPTY) $(PRIMARY_YDATA) $(NDATA) backward \
-		  `test $(DATAFORM) = vanguard || echo pacificnew`
+		  $$pacificnew
 		(grep '^#' tzdata.zi && echo && cat $(DATAFORM).zi) \
 		  >$@.dir/etcetera
 		touch -mr tzdata.zi $@.dir/etcetera
@@ -1291,9 +1312,9 @@ tzdata$(VERSION)-tailored.tar.gz: set-timestamps.out
 		    test -f $@.dir/$$file || links="$$links $$file"; \
 		  done && \
 		  ln $$links $@.dir
-		LC_ALL=C && export LC_ALL && \
+		$(SETUP_TAR) && \
 		  (cd $@.dir && \
-		   tar $(TARFLAGS) -cf - * | gzip $(GZIPFLAGS)) >$@.out
+		   $$TAR -cf - * | gzip $(GZIPFLAGS)) >$@.out
 		mv $@.out $@
 
 tzdb-$(VERSION).tar.lz: set-timestamps.out set-tzs-timestamp.out
@@ -1301,8 +1322,8 @@ tzdb-$(VERSION).tar.lz: set-timestamps.out set-tzs-timestamp.out
 		mkdir tzdb-$(VERSION)
 		ln $(ENCHILADA) tzdb-$(VERSION)
 		$(SET_TIMESTAMP) tzdb-$(VERSION) tzdb-$(VERSION)/*
-		LC_ALL=C && export LC_ALL && \
+		$(SETUP_TAR) && \
-		tar $(TARFLAGS) -cf - tzdb-$(VERSION) | lzip -9 >$@.out
+		$$TAR -cf - tzdb-$(VERSION) | lzip -9 >$@.out
 		mv $@.out $@
 
 tzcode$(VERSION).tar.gz.asc: tzcode$(VERSION).tar.gz
@@ -1313,22 +1334,21 @@ $(ALL_ASC):
 		$(GPG) --armor --detach-sign $?
 
 TYPECHECK_CFLAGS = $(CFLAGS) -DTYPECHECK -D__time_t_defined -D_TIME_T
-typecheck: typecheck_long_long typecheck_unsigned
+typecheck: long-long.ck unsigned.ck
-typecheck_long_long typecheck_unsigned: $(VERSION_DEPS)
+long-long.ck unsigned.ck: $(VERSION_DEPS)
-		rm -fr $@.dir
+		rm -fr $@d
-		mkdir $@.dir
+		mkdir $@d
-		ln $(VERSION_DEPS) $@.dir
+		ln $(VERSION_DEPS) $@d
-		cd $@.dir && \
+		cd $@d && \
 		  case $@ in \
-		    *_long_long) i="long long";; \
+		    long-long.*) i="long long";; \
-		    *_unsigned ) i="unsigned" ;; \
+		    unsigned.* ) i="unsigned" ;; \
 		  esac && \
-		  typecheck_cflags='' && \
 		  $(MAKE) \
 		    CFLAGS="$(TYPECHECK_CFLAGS) \"-Dtime_t=$$i\"" \
-		    TOPDIR="`pwd`" \
+		    TOPDIR="$$PWD" \
 		    install
-		$@.dir/zdump -i -c 1970,1971 Europe/Rome
+		$@d/zdump -i -c 1970,1971 Europe/Rome
 		touch $@
 
 zonenames:	tzdata.zi
@@ -1347,7 +1367,7 @@ zic.o:		private.h tzfile.h tzdir.h version.h
 .PHONY: check_web check_zishrink
 .PHONY: clean clean_misc commit-leap-seconds.list dummy.zd
 .PHONY: fetch-leap-seconds.list force_tzs
-.PHONY: install install_data maintainer-clean names
+.PHONY: install maintainer-clean names
 .PHONY: posix_only posix_right public
 .PHONY: rearguard_signatures rearguard_signatures_version
 .PHONY: rearguard_tarballs rearguard_tarballs_version

NEWS

@@ -1,5 +1,125 @@
 News for the tz database
 
+Release 2024b - 2024-09-04 12:27:47 -0700
+
+  Briefly:
+    Improve historical data for Mexico, Mongolia, and Portugal.
+    System V names are now obsolescent.
+    The main data form now uses %z.
+    The code now conforms to RFC 8536 for early timestamps.
+    Support POSIX.1-2024, which removes asctime_r and ctime_r.
+    Assume POSIX.2-1992 or later for shell scripts.
+    SUPPORT_C89 now defaults to 1.
+
+  Changes to past timestamps
+
+    Asia/Choibalsan is now an alias for Asia/Ulaanbaatar rather than
+    being a separate Zone with differing behavior before April 2008.
+    This seems better given our wildly conflicting information about
+    Mongolia's time zone history.  (Thanks to Heitor David Pinto.)
+
+    Historical transitions for Mexico have been updated based on
+    official Mexican decrees.  The affected timestamps occur during
+    the years 1921-1927, 1931, 1945, 1949-1970, and 1981-1997.
+    The affected zones are America/Bahia_Banderas, America/Cancun,
+    America/Chihuahua, America/Ciudad_Juarez, America/Hermosillo,
+    America/Mazatlan, America/Merida, America/Mexico_City,
+    America/Monterrey, America/Ojinaga, and America/Tijuana.
+    (Thanks to Heitor David Pinto.)
+
+    Historical transitions for Portugal, represented by Europe/Lisbon,
+    Atlantic/Azores, and Atlantic/Madeira, have been updated based on a
+    close reading of old Portuguese legislation, replacing previous data
+    mainly originating from Whitman and Shanks & Pottenger.  These
+    changes affect a few transitions in 1917-1921, 1924, and 1940
+    throughout these regions by a few hours or days, and various
+    timestamps between 1977 and 1993 depending on the region.  In
+    particular, the Azores and Madeira did not observe DST from 1977 to
+    1981.  Additionally, the adoption of standard zonal time in former
+    Portuguese colonies have been adjusted: Africa/Maputo in 1909, and
+    Asia/Dili by 22 minutes at the start of 1912.
+    (Thanks to Tim Parenti.)
+
+  Changes to past tm_isdst flags
+
+    The period from 1966-04-03 through 1966-10-02 in Portugal is now
+    modeled as DST, to more closely reflect how contemporaneous changes
+    in law entered into force.
+
+  Changes to data
+
+    Names present only for compatibility with UNIX System V
+    (last released in the 1990s) have been moved to 'backward'.
+    These names, which for post-1970 timestamps mostly just duplicate
+    data of geographical names, were confusing downstream uses.
+    Names moved to 'backward' are now links to geographical names.
+    This affects behavior for TZ='EET' for some pre-1981 timestamps,
+    for TZ='CET' for some pre-1947 timestamps, and for TZ='WET' for
+    some pre-1996 timestamps.  Also, TZ='MET' now behaves like
+    TZ='CET' and so uses the abbreviation "CET" rather than "MET".
+    Those needing the previous TZDB behavior, which does not match any
+    real-world clocks, can find the old entries in 'backzone'.
+    (Problem reported by Justin Grant.)
+
+    The main source files' time zone abbreviations now use %z,
+    supported by zic since release 2015f and used in vanguard form
+    since release 2022b.  For example, America/Sao_Paulo now contains
+    the zone continuation line "-3:00 Brazil %z", which is less error
+    prone than the old "-3:00 Brazil -03/-02".  This does not change
+    the represented data: the generated TZif files are unchanged.
+    Rearguard form still avoids %z, to support obsolescent parsers.
+
+    Asia/Almaty has been removed from zonenow.tab as it now agrees
+    with Asia/Tashkent for future timestamps, due to Kazakhstan's
+    2024-02-29 time zone change.  Similarly, America/Scoresbysund
+    has been removed, as it now agrees with America/Nuuk due to
+    its 2024-03-31 time zone change.
+
+  Changes to code
+
+    localtime.c now always uses a TZif file's time type 0 to handle
+    timestamps before the file's first transition.  Formerly,
+    localtime.c sometimes inferred a different time type, in order to
+    handle problematic data generated by zic 2018e or earlier.  As it
+    is now safe to assume more recent versions of zic, there is no
+    longer a pressing need to fail to conform RFC 8536 section 3.2,
+    which requires using time type 0 in this situation.  This change
+    does not affect behavior when reading TZif files generated by zic
+    2018f and later.
+
+    POSIX.1-2024 removes asctime_r and ctime_r and does not let
+    libraries define them, so remove them except when needed to
+    conform to earlier POSIX.  These functions are dangerous as they
+    can overrun user buffers.  If you still need them, add
+    -DSUPPORT_POSIX2008 to CFLAGS.
+
+    The SUPPORT_C89 option now defaults to 1 instead of 0, fixing a
+    POSIX-conformance bug introduced in 2023a.
+
+    tzselect now supports POSIX.1-2024 proleptic TZ strings.  Also, it
+    assumes POSIX.2-1992 or later, as practical porting targets now
+    all support that, and it uses some features from POSIX.1-2024 if
+    available.
+
+  Changes to build procedure
+
+    'make check' no longer requires curl and Internet access.
+
+    The build procedure now assumes POSIX.2-1992 or later, to simplify
+    maintenance.  To build on Solaris 10, the only extant system still
+    defaulting to pre-POSIX, prepend /usr/xpg4/bin to PATH.
+
+  Changes to documentation
+
+    The documentation now reflects POSIX.1-2024.
+
+  Changes to commentary
+
+    Commentary about historical transitions in Portugal and her former
+    colonies has been expanded with links to many relevant legislation.
+    (Thanks to Tim Parenti.)
+
+
 Release 2024a - 2024-02-01 09:28:56 -0800
 
   Briefly:
@@ -161,7 +281,7 @@ Release 2023d - 2023-12-21 20:02:24 -0800
      * It uses the special .POSIX target.
      * It quotes special characters more carefully.
      * It no longer mishandles builds in an ISO 8859 locale.
-    Due to the CC changes, TZDIR is now #defined in a file tzfile.h
+    Due to the CC changes, TZDIR is now #defined in a file tzdir.h
     built by 'make', not in a $(CC) -D option.  Also, TZDEFAULT is
     now treated like TZDIR as they have similar roles.
 
@@ -283,7 +403,7 @@ Release 2023a - 2023-03-22 12:39:33 -0700
     To improve tzselect diagnostics, zone1970.tab's comments column is
     now limited to countries that have multiple timezones.
 
-    Note that leap seconds are planned to be discontinued by 2035.
+    Note that there are plans to discontinue leap seconds by 2035.
 
 
 Release 2022g - 2022-11-29 08:58:31 -0800

asctime.c

@@ -1,4 +1,4 @@
-/* asctime and asctime_r a la POSIX and ISO C, except pad years before 1000.  */
+/* asctime a la ISO C.  */
 
 /*
 ** This file is in the public domain, so clarified as of
@@ -25,8 +25,8 @@
 ** leading zeroes to get the newline in the traditional place.
 ** The -4 ensures that we get four characters of output even if
 ** we call a strftime variant that produces fewer characters for some years.
-** The ISO C and POSIX standards prohibit padding the year,
+** This conforms to recent ISO C and POSIX standards, which say behavior
-** but many implementations pad anyway; most likely the standards are buggy.
+** is undefined when the year is less than 1000 or greater than 9999.
 */
 static char const ASCTIME_FMT[] = "%s %s%3d %.2d:%.2d:%.2d %-4s\n";
 /*
@@ -60,6 +60,18 @@ static char buf_asctime[2*3 + 5*INT_STRLEN_MAXIMUM(int) + 7 + 2 + 1 + 1];
 static char buf_ctime[sizeof buf_asctime];
 #endif
 
+/* Publish asctime_r and ctime_r only when supporting older POSIX.  */
+#if SUPPORT_POSIX2008
+# define asctime_static
+#else
+# define asctime_static static
+# undef asctime_r
+# undef ctime_r
+# define asctime_r static_asctime_r
+# define ctime_r static_ctime_r
+#endif
+
+asctime_static
 char *
 asctime_r(struct tm const *restrict timeptr, char *restrict buf)
 {
@@ -116,6 +128,7 @@ asctime(register const struct tm *timeptr)
 	return asctime_r(timeptr, buf_asctime);
 }
 
+asctime_static
 char *
 ctime_r(const time_t *timep, char *buf)
 {

localtime.c

@@ -106,7 +106,7 @@ static char const UNSPEC[] = "-00";
    for ttunspecified to work without crashing.  */
 enum { CHARS_EXTRA = max(sizeof UNSPEC, 2) - 1 };
 
-/* Limit to time zone abbreviation length in POSIX.1-2017-style TZ strings.
+/* Limit to time zone abbreviation length in proleptic TZ strings.
    This is distinct from TZ_MAX_CHARS, which limits TZif file contents.  */
 #ifndef TZNAME_MAXIMUM
 # define TZNAME_MAXIMUM 255
@@ -130,11 +130,6 @@ struct state {
 	char chars[max(max(TZ_MAX_CHARS + CHARS_EXTRA, sizeof "UTC"),
 		       2 * (TZNAME_MAXIMUM + 1))];
 	struct lsinfo	lsis[TZ_MAX_LEAPS];
-
-	/* The time type to use for early times or if no transitions.
-	   It is always zero for recent tzdb releases.
-	   It might be nonzero for data from tzdb 2018e or earlier.  */
-	int defaulttype;
 };
 
 enum r_type {
@@ -187,8 +182,9 @@ static int		lcl_is_set;
 **	objects: a broken-down time structure and an array of char.
 ** Thanks to Paul Eggert for noting this.
 **
-** This requirement was removed in C99, so support it only if requested,
+** Although this requirement was removed in C99 it is still present in POSIX.
-** as support is more likely to lead to bugs in badly written programs.
+** Follow the requirement if SUPPORT_C89, even though this is more likely to
+** trigger latent bugs in programs.
 */
 
 #if SUPPORT_C89
@@ -710,58 +706,6 @@ tzloadbody(char const *name, struct state *sp, bool doextend,
 	if (sp->typecnt == 0)
 	  return EINVAL;
 
-	/* Infer sp->defaulttype from the data.  Although this default
-	   type is always zero for data from recent tzdb releases,
-	   things are trickier for data from tzdb 2018e or earlier.
-
-	   The first set of heuristics work around bugs in 32-bit data
-	   generated by tzdb 2013c or earlier.  The workaround is for
-	   zones like Australia/Macquarie where timestamps before the
-	   first transition have a time type that is not the earliest
-	   standard-time type.  See:
-	   https://mm.icann.org/pipermail/tz/2013-May/019368.html */
-	/*
-	** If type 0 does not specify local time, or is unused in transitions,
-	** it's the type to use for early times.
-	*/
-	for (i = 0; i < sp->timecnt; ++i)
-		if (sp->types[i] == 0)
-			break;
-	i = i < sp->timecnt && ! ttunspecified(sp, 0) ? -1 : 0;
-	/*
-	** Absent the above,
-	** if there are transition times
-	** and the first transition is to a daylight time
-	** find the standard type less than and closest to
-	** the type of the first transition.
-	*/
-	if (i < 0 && sp->timecnt > 0 && sp->ttis[sp->types[0]].tt_isdst) {
-		i = sp->types[0];
-		while (--i >= 0)
-			if (!sp->ttis[i].tt_isdst)
-				break;
-	}
-	/* The next heuristics are for data generated by tzdb 2018e or
-	   earlier, for zones like EST5EDT where the first transition
-	   is to DST.  */
-	/*
-	** If no result yet, find the first standard type.
-	** If there is none, punt to type zero.
-	*/
-	if (i < 0) {
-		i = 0;
-		while (sp->ttis[i].tt_isdst)
-			if (++i >= sp->typecnt) {
-				i = 0;
-				break;
-			}
-	}
-	/* A simple 'sp->defaulttype = 0;' would suffice here if we
-	   didn't have to worry about 2018e-or-earlier data.  Even
-	   simpler would be to remove the defaulttype member and just
-	   use 0 in its place.  */
-	sp->defaulttype = i;
-
 	return 0;
 }
 
@@ -807,7 +751,7 @@ is_digit(char c)
 ** Return a pointer to that character.
 */
 
-ATTRIBUTE_REPRODUCIBLE static const char *
+ATTRIBUTE_PURE_114833 static const char *
 getzname(register const char *strp)
 {
 	register char	c;
@@ -828,7 +772,7 @@ getzname(register const char *strp)
 ** We don't do any checking here; checking is done later in common-case code.
 */
 
-ATTRIBUTE_REPRODUCIBLE static const char *
+ATTRIBUTE_PURE_114833 static const char *
 getqzname(register const char *strp, const int delim)
 {
 	register int	c;
@@ -1080,7 +1024,7 @@ transtime(const int year, register const struct rule *const rulep,
 }
 
 /*
-** Given a POSIX.1-2017-style TZ string, fill in the rule tables as
+** Given a POSIX.1 proleptic TZ string, fill in the rule tables as
 ** appropriate.
 */
 
@@ -1183,11 +1127,13 @@ tzparse(const char *name, struct state *sp, struct state const *basep)
 			do {
 			  int_fast32_t yearsecs
 			    = year_lengths[isleap(yearbeg - 1)] * SECSPERDAY;
+			  time_t janfirst1 = janfirst;
 			  yearbeg--;
-			  if (increment_overflow_time(&janfirst, -yearsecs)) {
+			  if (increment_overflow_time(&janfirst1, -yearsecs)) {
 			    janoffset = -yearsecs;
 			    break;
 			  }
+			  janfirst = janfirst1;
 			} while (atlo < janfirst
 				 && EPOCH_YEAR - YEARSPERREPEAT / 2 < yearbeg);
 
@@ -1313,7 +1259,7 @@ tzparse(const char *name, struct state *sp, struct state const *basep)
 					/*
 					** Transitions from DST to DDST
 					** will effectively disappear since
-					** POSIX.1-2017 provides for only one
+					** proleptic TZ strings have only one
 					** DST offset.
 					*/
 					if (isdst && !sp->ttis[j].tt_ttisstd) {
@@ -1342,7 +1288,6 @@ tzparse(const char *name, struct state *sp, struct state const *basep)
 		sp->timecnt = 0;
 		init_ttinfo(&sp->ttis[0], -stdoffset, false, 0);
 	}
-	sp->defaulttype = 0;
 	sp->charcnt = charcnt;
 	cp = sp->chars;
 	memcpy(cp, stdname, stdlen);
@@ -1378,7 +1323,6 @@ zoneinit(struct state *sp, char const *name)
     sp->goback = sp->goahead = false;
     init_ttinfo(&sp->ttis[0], 0, false, 0);
     strcpy(sp->chars, utc);
-    sp->defaulttype = 0;
     return 0;
   } else {
     int err = tzload(name, sp, true);
@@ -1465,8 +1409,8 @@ tzfree(timezone_t sp)
 }
 
 /*
-** NetBSD 6.1.4 has ctime_rz, but omit it because POSIX says ctime and
+** NetBSD 6.1.4 has ctime_rz, but omit it because C23 deprecates ctime and
-** ctime_r are obsolescent and have potential security problems that
+** POSIX.1-2024 removes ctime_r.  Both have potential security problems that
 ** ctime_rz would share.  Callers can instead use localtime_rz + strftime.
 **
 ** NetBSD 6.1.4 has tzgetname, but omit it because it doesn't work
@@ -1484,8 +1428,7 @@ tzfree(timezone_t sp)
 **
 ** If successful and SETNAME is nonzero,
 ** set the applicable parts of tzname, timezone and altzone;
-** however, it's OK to omit this step
+** however, it's OK to omit this step for proleptic TZ strings
-** if the timezone is compatible with POSIX.1-2017
 ** since in that case tzset should have already done this step correctly.
 ** SETNAME's type is int_fast32_t for compatibility with gmtsub,
 ** but it is actually a boolean and its value should be 0 or 1.
@@ -1553,7 +1496,7 @@ localsub(struct state const *sp, time_t const *timep, int_fast32_t setname,
 			return result;
 	}
 	if (sp->timecnt == 0 || t < sp->ats[0]) {
-		i = sp->defaulttype;
+		i = 0;
 	} else {
 		register int	lo = 1;
 		register int	hi = sp->timecnt;
@@ -2285,7 +2228,7 @@ mktime(struct tm *tmp)
 }
 
 #if STD_INSPIRED
-/* This function is obsolescent and may disapper in future releases.
+/* This function is obsolescent and may disappear in future releases.
    Callers can instead use mktime.  */
 time_t
 timelocal(struct tm *tmp)
@@ -2303,7 +2246,7 @@ timelocal(struct tm *tmp)
 # define EXTERN_TIMEOFF static
 #endif
 
-/* This function is obsolescent and may disapper in future releases.
+/* This function is obsolescent and may disappear in future releases.
    Callers can instead use mktime_z with a fixed-offset zone.  */
 EXTERN_TIMEOFF time_t
 timeoff(struct tm *tmp, long offset)

newctime.3

@@ -9,16 +9,16 @@ asctime, ctime, difftime, gmtime, localtime, mktime \- convert date and time
 .el .ds - \-
 .B #include <time.h>
 .PP
-.BR "extern char *tzname[];" " /\(** (optional) \(**/"
-.PP
 .B [[deprecated]] char *ctime(time_t const *clock);
 .PP
+/* Only in POSIX.1-2017 and earlier.  */
 .B char *ctime_r(time_t const *clock, char *buf);
 .PP
 .B double difftime(time_t time1, time_t time0);
 .PP
 .B [[deprecated]] char *asctime(struct tm const *tm);
 .PP
+/* Only in POSIX.1-2017 and earlier.  */
 .B "char *asctime_r(struct tm const *restrict tm,"
 .B "    char *restrict result);"
 .PP
@@ -112,17 +112,6 @@ The
 function
 corrects for the time zone and any time zone adjustments
 (such as Daylight Saving Time in the United States).
-After filling in the
-.q "tm"
-structure,
-.B localtime
-sets the
-.BR tm_isdst 'th
-element of
-.B tzname
-to a pointer to a string that's the time zone abbreviation to be used with
-.BR localtime 's
-return value.
 .PP
 The
 .B gmtime
@@ -191,9 +180,19 @@ are determined.
 The
 .B mktime
 function
-returns the specified calendar time;
+returns the specified calendar time.
 If the calendar time cannot be represented,
-it returns \-1.
+it returns \-1 without updating the structure.
+To distinguish failure from a valid \-1 return,
+you can set
+.B tm_wday
+or
+.B tm_yday
+to a negative value before calling
+.BR mktime ;
+if that value is still negative when
+.B mktime
+returns, the calendar time could not be represented.
 .PP
 The
 .B difftime
@@ -213,6 +212,13 @@ and
 functions
 are like their unsuffixed counterparts, except that they accept an
 additional argument specifying where to store the result if successful.
+The
+.B ctime_r
+and
+.B asctime_r
+functions are present only on systems supporting POSIX.1-2017 and earlier,
+as they are removed in POSIX.1-2024 and user code can define these
+functions with other meanings.
 .PP
 The
 .B localtime_rz
@@ -275,21 +281,43 @@ from UT, with positive values indicating east
 of the Prime Meridian.
 The field's name is derived from Greenwich Mean Time, a precursor of UT.
 .PP
-In
+In platforms conforming to POSIX.1-2024 the
 .B "struct tm"
 the
 .B tm_zone
 and
 .B tm_gmtoff
-fields exist, and are filled in, only if arrangements to do
+fields exist, and are filled in.
-so were made when the library containing these functions was
+For
-created.
+.B localtime_rz
-Similarly, the
+and
-.B tzname
+.B mktime_rz
-variable is optional; also, there is no guarantee that
+the storage lifetime of the strings addressed by
-.B tzname
+.B tm_zone
-will
+extends until the corresponding
-continue to exist in this form in future releases of this code.
+.B timezone_t
+object is freed via
+.BR tzfree .
+For the other functions the lifetime extends until the
+.I TZ
+environment variable changes state and
+.B tzset
+is then called.
+.PP
+As a side effect, the
+.BR ctime ,
+.B localtime
+and
+.B mktime
+functions also behave as if
+.B tzset
+were called.
+The
+.B ctime_r
+and
+.B localtime_r
+functions might (or might not) also behave this way.
+This is for compatibility with older platforms, as required by POSIX.
 .SH FILES
 .ta \w'/usr/share/zoneinfo/posixrules\0\0'u
 /etc/localtime	local timezone file
@@ -303,11 +331,11 @@ continue to exist in this form in future releases of this code.
 If /usr/share/zoneinfo/GMT is absent,
 UTC leap seconds are loaded from /usr/share/zoneinfo/GMT0 if present.
 .SH SEE ALSO
-getenv(3),
+.BR getenv (3),
-newstrftime(3),
+.BR newstrftime (3),
-newtzset(3),
+.BR newtzset (3),
-time(2),
+.BR time (2),
-tzfile(5)
+.BR tzfile (5).
 .SH NOTES
 The return values of
 .BR asctime ,
@@ -317,20 +345,6 @@ and
 .B localtime
 point to static data
 overwritten by each call.
-The
-.B tzname
-variable (once set) and the
-.B tm_zone
-field of a returned
-.B "struct tm"
-both point to an array of characters that
-can be freed or overwritten by later calls to the functions
-.BR localtime ,
-.BR tzfree ,
-and
-.BR tzset ,
-if these functions affect the timezone information that specifies the
-abbreviation in question.
 The remaining functions and data are thread-safe.
 .PP
 The

newctime.3.txt

@@ -7,16 +7,16 @@ NAME
 SYNOPSIS
        #include <time.h>
 
-       extern char *tzname[]; /* (optional) */
-
        [[deprecated]] char *ctime(time_t const *clock);
 
+       /* Only in POSIX.1-2017 and earlier.  */
        char *ctime_r(time_t const *clock, char *buf);
 
        double difftime(time_t time1, time_t time0);
 
        [[deprecated]] char *asctime(struct tm const *tm);
 
+       /* Only in POSIX.1-2017 and earlier.  */
        char *asctime_r(struct tm const *restrict tm,
            char *restrict result);
 
@@ -68,9 +68,7 @@ DESCRIPTION
        The localtime and gmtime functions return pointers to "tm" structures,
        described below.  The localtime function corrects for the time zone and
        any time zone adjustments (such as Daylight Saving Time in the United
-       States).  After filling in the "tm" structure, localtime sets the
+       States).
-       tm_isdst'th element of tzname to a pointer to a string that's the time
-       zone abbreviation to be used with localtime's return value.
 
        The gmtime function converts to Coordinated Universal Time.
 
@@ -96,15 +94,22 @@ DESCRIPTION
        set to represent the specified calendar time, but with their values
        forced to their normal ranges; the final value of tm_mday is not set
        until tm_mon and tm_year are determined.  The mktime function returns
-       the specified calendar time; If the calendar time cannot be
+       the specified calendar time.  If the calendar time cannot be
-       represented, it returns -1.
+       represented, it returns -1 without updating the structure.  To
+       distinguish failure from a valid -1 return, you can set tm_wday or
+       tm_yday to a negative value before calling mktime; if that value is
+       still negative when mktime returns, the calendar time could not be
+       represented.
 
        The difftime function returns the difference between two calendar
        times, (time1 - time0), expressed in seconds.
 
        The ctime_r, localtime_r, gmtime_r, and asctime_r functions are like
        their unsuffixed counterparts, except that they accept an additional
-       argument specifying where to store the result if successful.
+       argument specifying where to store the result if successful.  The
+       ctime_r and asctime_r functions are present only on systems supporting
+       POSIX.1-2017 and earlier, as they are removed in POSIX.1-2024 and user
+       code can define these functions with other meanings.
 
        The localtime_rz and mktime_z functions are like their unsuffixed
        counterparts, except that they accept an extra initial zone argument
@@ -136,11 +141,17 @@ DESCRIPTION
        The field's name is derived from Greenwich Mean Time, a precursor of
        UT.
 
-       In struct tm the tm_zone and tm_gmtoff fields exist, and are filled in,
+       In platforms conforming to POSIX.1-2024 the struct tm the tm_zone and
-       only if arrangements to do so were made when the library containing
+       tm_gmtoff fields exist, and are filled in.  For localtime_rz and
-       these functions was created.  Similarly, the tzname variable is
+       mktime_rz the storage lifetime of the strings addressed by tm_zone
-       optional; also, there is no guarantee that tzname will continue to
+       extends until the corresponding timezone_t object is freed via tzfree.
-       exist in this form in future releases of this code.
+       For the other functions the lifetime extends until the TZ environment
+       variable changes state and tzset is then called.
+
+       As a side effect, the ctime, localtime and mktime functions also behave
+       as if tzset were called.  The ctime_r and localtime_r functions might
+       (or might not) also behave this way.  This is for compatibility with
+       older platforms, as required by POSIX.
 
 FILES
        /etc/localtime                  local timezone file
@@ -152,16 +163,12 @@ FILES
        /usr/share/zoneinfo/GMT0 if present.
 
 SEE ALSO
-       getenv(3), newstrftime(3), newtzset(3), time(2), tzfile(5)
+       getenv(3), newstrftime(3), newtzset(3), time(2), tzfile(5).
 
 NOTES
        The return values of asctime, ctime, gmtime, and localtime point to
-       static data overwritten by each call.  The tzname variable (once set)
+       static data overwritten by each call.  The remaining functions and data
-       and the tm_zone field of a returned struct tm both point to an array of
+       are thread-safe.
-       characters that can be freed or overwritten by later calls to the
-       functions localtime, tzfree, and tzset, if these functions affect the
-       timezone information that specifies the abbreviation in question.  The
-       remaining functions and data are thread-safe.
 
        The asctime, asctime_r, ctime, and ctime_r functions behave strangely
        for years before 1000 or after 9999.  The 1989 and 1999 editions of the

newstrftime.3

@@ -91,11 +91,11 @@ as specified by brackets in the description.
 If a bracketed member name is followed by
 .q + ,
 .B strftime
-can use the named member even though POSIX.1-2017 does not list it;
+can use the named member even though POSIX.1-2024 does not list it;
 if the name is followed by
 .q \*- ,
 .B strftime
-ignores the member even though POSIX.1-2017 lists it
+ignores the member even though POSIX.1-2024 lists it
 which means portable code should set it.
 For portability,
 .BI * timeptr
@@ -137,8 +137,8 @@ is replaced by the locale's appropriate date and time representation.
 .IR tm_hour ,
 .IR tm_min ,
 .IR tm_sec ,
-.IR tm_gmtoff +,
+.IR tm_gmtoff ,
-.IR tm_zone +,
+.IR tm_zone ,
 .IR tm_isdst \*-].
 .TP
 %D
@@ -326,8 +326,8 @@ is replaced by the locale's appropriate time representation.
 .IR tm_hour ,
 .IR tm_min ,
 .IR tm_sec ,
-.IR tm_gmtoff +,
+.IR tm_gmtoff ,
-.IR tm_zone +,
+.IR tm_zone ,
 .IR tm_isdst \*-].
 .TP
 %x
@@ -355,7 +355,7 @@ is replaced by the year without century as a decimal number [00,99].
 %Z
 is replaced by the time zone abbreviation,
 or by the empty string if this is not determinable.
-.RI [ tm_zone +,
+.RI [ tm_zone ,
 .IR tm_isdst \*-]
 .TP
 %z
@@ -369,7 +369,7 @@ but local time is indeterminate; by convention this is used for
 locations while uninhabited, and corresponds to a zero offset when the
 time zone abbreviation begins with
 .q "\*-" .
-.RI [ tm_gmtoff +,
+.RI [ tm_gmtoff ,
 .IR tm_zone +,
 .IR tm_isdst \*-]
 .TP
@@ -398,7 +398,7 @@ also behaves as if
 were called.
 This is for compatibility with older platforms, as required by POSIX;
 it is not needed for
-.BR tzset 's
+.BR strftime 's
 own use.
 .SH "RETURN VALUE"
 If the conversion is successful,
@@ -428,11 +428,11 @@ conversion and the number of seconds since the Epoch cannot be represented
 in a
 .c time_t .
 .SH SEE ALSO
-date(1),
+.BR date (1),
-getenv(3),
+.BR getenv (3),
-newctime(3),
+.BR newctime (3),
-newtzset(3),
+.BR newtzset (3),
-time(2),
+.BR time (2),
-tzfile(5)
+.BR tzfile (5).
 .SH BUGS
 There is no conversion specification for the phase of the moon.

newstrftime.3.txt

@@ -26,9 +26,9 @@ DESCRIPTION
        which are then copied into the array.  The characters depend on the
        values of zero or more members of *timeptr as specified by brackets in
        the description.  If a bracketed member name is followed by "+",
-       strftime can use the named member even though POSIX.1-2017 does not
+       strftime can use the named member even though POSIX.1-2024 does not
        list it; if the name is followed by "-", strftime ignores the member
-       even though POSIX.1-2017 lists it which means portable code should set
+       even though POSIX.1-2024 lists it which means portable code should set
        it.  For portability, *timeptr should be initialized as if by a
        successful call to gmtime, localtime, mktime, timegm, or similar
        functions.
@@ -48,7 +48,7 @@ DESCRIPTION
 
        %c     is   replaced   by   the  locale's  appropriate  date  and  time
               representation.  [tm_year, tm_yday,  tm_mon,  tm_mday,  tm_wday,
-              tm_hour, tm_min, tm_sec, tm_gmtoff+, tm_zone+, tm_isdst-].
+              tm_hour, tm_min, tm_sec, tm_gmtoff, tm_zone, tm_isdst-].
 
        %D     is equivalent to %m/%d/%y.  [tm_year, tm_mon, tm_mday]
 
@@ -139,7 +139,7 @@ DESCRIPTION
 
        %X     is  replaced  by  the  locale's appropriate time representation.
               [tm_year-,  tm_yday-,  tm_mon-,  tm_mday-,  tm_wday-,   tm_hour,
-              tm_min, tm_sec, tm_gmtoff+, tm_zone+, tm_isdst-].
+              tm_min, tm_sec, tm_gmtoff, tm_zone, tm_isdst-].
 
        %x     is  replaced  by  the  locale's appropriate date representation.
               [tm_year, tm_yday, tm_mon, tm_mday, tm_wday, tm_hour-,  tm_min-,
@@ -152,7 +152,7 @@ DESCRIPTION
               [00,99].  [tm_year]
 
        %Z     is  replaced  by  the  time  zone  abbreviation, or by the empty
-              string if this is not determinable.  [tm_zone+, tm_isdst-]
+              string if this is not determinable.  [tm_zone, tm_isdst-]
 
        %z     is replaced by the offset from the Prime Meridian in the  format
               +HHMM  or  -HHMM (ISO 8601) as appropriate, with positive values
@@ -161,7 +161,7 @@ DESCRIPTION
               -0000 is used when the time is Universal Time but local time  is
               indeterminate;  by  convention  this is used for locations while
               uninhabited, and corresponds to a zero offset when the time zone
-              abbreviation begins with "-".  [tm_gmtoff+, tm_zone+, tm_isdst-]
+              abbreviation begins with "-".  [tm_gmtoff, tm_zone+, tm_isdst-]
 
        %%     is replaced by a single %.
 
@@ -171,7 +171,7 @@ DESCRIPTION
 
        As a side effect, strftime also behaves as if tzset were called.   This
        is  for compatibility with older platforms, as required by POSIX; it is
-       not needed for tzset's own use.
+       not needed for strftime's own use.
 
 RETURN VALUE
        If the conversion is successful, strftime returns the number  of  bytes
@@ -194,7 +194,7 @@ ERRORS
               since the Epoch cannot be represented in a time_t.
 
 SEE ALSO
-       date(1), getenv(3), newctime(3), newtzset(3), time(2), tzfile(5)
+       date(1), getenv(3), newctime(3), newtzset(3), time(2), tzfile(5).
 
 BUGS
        There is no conversion specification for the phase of the moon.

newtzset.3

@@ -15,6 +15,14 @@ tzset \- initialize time conversion information
 .PP
 .B void tzset(void);
 .PP
+/\(** Optional and obsolescent:  \(**/
+.br
+.B extern char *tzname[];
+.br
+.B extern long timezone;
+.br
+.B extern int daylight;
+.PP
 .B cc ... \*-ltz
 .fi
 .SH DESCRIPTION
@@ -165,7 +173,7 @@ describes when the change back happens.  Each
 .I time
 field describes when, in current local time, the change to the other
 time is made.
-As an extension to POSIX.1-2017, daylight saving is assumed to be in effect
+Daylight saving is assumed to be in effect
 all year if it begins January 1 at 00:00 and ends December 31 at
 24:00 plus the difference between daylight saving and standard time,
 leaving no room for standard time in the calendar.
@@ -212,11 +220,7 @@ The
 .I time
 has the same format as
 .I offset
-except that POSIX.1-2017 does not allow a leading sign (\c
+except that the hours part of
-.q "\*-"
-or
-.q "+" ).
-As an extension to POSIX.1-2017, the hours part of
 .I time
 can range from \-167 through 167; this allows for unusual rules such
 as
@@ -229,8 +233,7 @@ is not given, is
 .LP
 Here are some examples of
 .I TZ
-values that directly specify the timezone; they use some of the
+values that directly specify the timezone.
-extensions to POSIX.1-2017.
 .TP
 .B EST5
 stands for US Eastern Standard
@@ -346,6 +349,22 @@ if the implied call to
 fails,
 .B tzset
 falls back on UT.
+.PP
+As a side effect, the
+.B tzset
+function sets some external variables if the platform defines them.
+It sets
+.BR tzname [0]
+and
+.BR tzname [1]
+to pointers to strings that are time zone abbreviations to be used with
+standard and daylight saving time, respectively.
+It also sets
+.B timezone
+to be the number of seconds that standard time is west of the Prime Meridian,
+and
+.B daylight
+to be zero if daylight saving time is never in effect, non-zero otherwise.
 .SH "RETURN VALUE"
 If successful, the
 .B tzalloc
@@ -384,8 +403,29 @@ and
 If /usr/share/zoneinfo/GMT is absent,
 UTC leap seconds are loaded from /usr/share/zoneinfo/GMT0 if present.
 .SH SEE ALSO
-getenv(3),
+.BR getenv (3),
-newctime(3),
+.BR newctime (3),
-newstrftime(3),
+.BR newstrftime (3),
-time(2),
+.BR time (2),
-tzfile(5)
+.BR tzfile (5).
+.SH NOTES
+Portable code should not rely on the contents of the external variables
+.BR tzname ,
+.B timezone
+and
+.B daylight
+as their contents are unspecified (and do not make sense in general)
+when a geographical TZ is used.
+In multithreaded applications behavior is undefined if one thread accesses
+one of these variables while another thread invokes
+.BR tzset .
+A future version of POSIX is planned to remove these variables;
+callers can instead use the
+.I tm_gmtoff
+and
+.I tm_zone
+members of
+.B struct tm,
+or use
+.B strftime
+with "%z" or "%Z".

newtzset.3.txt

@@ -12,6 +12,11 @@ SYNOPSIS
 
        void tzset(void);
 
+       /* Optional and obsolescent:  */
+       extern char *tzname[];
+       extern long timezone;
+       extern int daylight;
+
        cc ... -ltz
 
 DESCRIPTION
@@ -88,12 +93,11 @@ DESCRIPTION
                      standard  to  daylight  saving time occurs and the second
                      date describes when the change back happens.   Each  time
                      field  describes  when, in current local time, the change
-                     to  the  other  time  is  made.   As  an   extension   to
+                     to the other time is made.  Daylight saving is assumed to
-                     POSIX.1-2017,  daylight saving is assumed to be in effect
+                     be in effect all year if it begins January 1 at 00:00 and
-                     all year if  it  begins  January  1  at  00:00  and  ends
+                     ends December 31 at 24:00  plus  the  difference  between
-                     December 31 at 24:00 plus the difference between daylight
+                     daylight  saving  and  standard time, leaving no room for
-                     saving  and  standard  time, leaving no room for standard
+                     standard time in the calendar.
-                     time in the calendar.
 
                      The format of date is one of the following:
 
@@ -114,15 +118,13 @@ DESCRIPTION
                             is  the  first  week in which the d'th day occurs.
                             Day zero is Sunday.
 
-                     The time has  the  same  format  as  offset  except  that
+                     The time has the same format as offset  except  that  the
-                     POSIX.1-2017  does not allow a leading sign ("-" or "+").
+                     hours  part of time can range from -167 through 167; this
-                     As an extension to POSIX.1-2017, the hours part  of  time
+                     allows for unusual rules such as "the Saturday before the
-                     can  range from -167 through 167; this allows for unusual
+                     first Sunday of March".  The  default,  if  time  is  not
-                     rules such as "the Saturday before the  first  Sunday  of
+                     given, is 02:00:00.
-                     March".  The default, if time is not given, is 02:00:00.
 
-       Here are some examples of TZ values that directly specify the timezone;
+       Here are some examples of TZ values that directly specify the timezone.
-       they use some of the extensions to POSIX.1-2017.
 
        EST5   stands  for  US  Eastern Standard Time (EST), 5 hours behind UT,
               without daylight saving.
@@ -183,6 +185,14 @@ DESCRIPTION
        getenv fails, tzset acts like tzalloc(nullptr); if the implied call  to
        tzalloc fails, tzset falls back on UT.
 
+       As  a  side  effect, the tzset function sets some external variables if
+       the platform defines them.  It sets tzname[0] and tzname[1] to pointers
+       to strings that are time zone abbreviations to be  used  with  standard
+       and  daylight  saving  time, respectively.  It also sets timezone to be
+       the number of seconds that standard time is west of the Prime Meridian,
+       and daylight to be zero if daylight saving time  is  never  in  effect,
+       non-zero otherwise.
+
 RETURN VALUE
        If  successful,  the  tzalloc function returns a nonnull pointer to the
        newly allocated object.  Otherwise, it returns a null pointer and  sets
@@ -208,6 +218,16 @@ FILES
        /usr/share/zoneinfo/GMT0 if present.
 
 SEE ALSO
-       getenv(3), newctime(3), newstrftime(3), time(2), tzfile(5)
+       getenv(3), newctime(3), newstrftime(3), time(2), tzfile(5).
+
+NOTES
+       Portable code should not rely on the contents of the external variables
+       tzname, timezone and daylight as their contents are unspecified (and do
+       not make sense  in  general)  when  a  geographical  TZ  is  used.   In
+       multithreaded applications behavior is undefined if one thread accesses
+       one  of  these  variables while another thread invokes tzset.  A future
+       version of POSIX is planned to  remove  these  variables;  callers  can
+       instead  use  the  tm_gmtoff  and  tm_zone members of struct tm, or use
+       strftime with "%z" or "%Z".
 
 Time Zone Database                                                 newtzset(3)

private.h

@@ -19,19 +19,22 @@
 
 /* PORT_TO_C89 means the code should work even if the underlying
    compiler and library support only C89 plus C99's 'long long'
-   and perhaps a few other extensions to C89.  SUPPORT_C89 means the
+   and perhaps a few other extensions to C89.
-   tzcode library should support C89 callers in addition to the usual
+
-   support for C99-and-later callers; however, C89 support can trigger
+   This macro is obsolescent, and the plan is to remove it along with
-   latent bugs in C99-and-later callers.  These macros are obsolescent,
+   associated code.  A good time to do that might be in the year 2029
-   and the plan is to remove them along with any code needed only when
-   they are nonzero.  A good time to do that might be in the year 2029
    because RHEL 7 (whose GCC defaults to C89) extended life cycle
    support (ELS) is scheduled to end on 2028-06-30.  */
 #ifndef PORT_TO_C89
 # define PORT_TO_C89 0
 #endif
+
+/* SUPPORT_C89 means the tzcode library should support C89 callers
+   in addition to the usual support for C99-and-later callers.
+   This defaults to 1 as POSIX requires, even though that can trigger
+   latent bugs in callers.  */
 #ifndef SUPPORT_C89
-# define SUPPORT_C89 0
+# define SUPPORT_C89 1
 #endif
 
 #ifndef __STDC_VERSION__
@@ -69,10 +72,6 @@
 ** You can override these in your C compiler options, e.g. '-DHAVE_GETTEXT=1'.
 */
 
-#ifndef HAVE_DECL_ASCTIME_R
-# define HAVE_DECL_ASCTIME_R 1
-#endif
-
 #if !defined HAVE__GENERIC && defined __has_extension
 # if !__has_extension(c_generic_selections)
 #  define HAVE__GENERIC 0
@@ -236,6 +235,31 @@
 # include <unistd.h> /* for R_OK, and other POSIX goodness */
 #endif /* HAVE_UNISTD_H */
 
+/* SUPPORT_POSIX2008 means the tzcode library should support
+   POSIX.1-2017-and-earlier callers in addition to the usual support for
+   POSIX.1-2024-and-later callers; however, this can be
+   incompatible with POSIX.1-2024-and-later callers.
+   This macro is obsolescent, and the plan is to remove it
+   along with any code needed only when it is nonzero.
+   A good time to do that might be in the year 2034.
+   This macro's name is SUPPORT_POSIX2008 because _POSIX_VERSION == 200809
+   in POSIX.1-2017, a minor revision of POSIX.1-2008.  */
+#ifndef SUPPORT_POSIX2008
+# if defined _POSIX_VERSION && _POSIX_VERSION <= 200809
+#  define SUPPORT_POSIX2008 1
+# else
+#  define SUPPORT_POSIX2008 0
+# endif
+#endif
+
+#ifndef HAVE_DECL_ASCTIME_R
+# if SUPPORT_POSIX2008
+#  define HAVE_DECL_ASCTIME_R 1
+# else
+#  define HAVE_DECL_ASCTIME_R 0
+# endif
+#endif
+
 #ifndef HAVE_STRFTIME_L
 # if _POSIX_VERSION < 200809
 #  define HAVE_STRFTIME_L 0
@@ -460,14 +484,6 @@ typedef unsigned long uintmax_t;
 # define ckd_mul(r, a, b) __builtin_mul_overflow(a, b, r)
 #endif
 
-#if 3 <= __GNUC__
-# define ATTRIBUTE_MALLOC __attribute__((malloc))
-# define ATTRIBUTE_FORMAT(spec) __attribute__((format spec))
-#else
-# define ATTRIBUTE_MALLOC /* empty */
-# define ATTRIBUTE_FORMAT(spec) /* empty */
-#endif
-
 #if (defined __has_c_attribute \
      && (202311 <= __STDC_VERSION__ || !defined __STRICT_ANSI__))
 # define HAVE___HAS_C_ATTRIBUTE true
@@ -535,24 +551,27 @@ typedef unsigned long uintmax_t;
 # endif
 #endif
 #ifndef ATTRIBUTE_REPRODUCIBLE
-# if 3 <= __GNUC__
+# define ATTRIBUTE_REPRODUCIBLE /* empty */
-#  define ATTRIBUTE_REPRODUCIBLE __attribute__((pure))
-# else
-#  define ATTRIBUTE_REPRODUCIBLE /* empty */
-# endif
 #endif
 
-#if HAVE___HAS_C_ATTRIBUTE
+/* GCC attributes that are useful in tzcode.
-# if __has_c_attribute(unsequenced)
+   __attribute__((pure)) is stricter than [[reproducible]],
-#  define ATTRIBUTE_UNSEQUENCED [[unsequenced]]
+   so the latter is an adequate substitute in non-GCC C23 platforms.  */
-# endif
+#if __GNUC__ < 3
+# define ATTRIBUTE_FORMAT(spec) /* empty */
+# define ATTRIBUTE_PURE ATTRIBUTE_REPRODUCIBLE
+#else
+# define ATTRIBUTE_FORMAT(spec) __attribute__((format spec))
+# define ATTRIBUTE_PURE __attribute__((pure))
 #endif
-#ifndef ATTRIBUTE_UNSEQUENCED
+
-# if 3 <= __GNUC__
+/* Avoid GCC bug 114833 <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114833>.
-#  define ATTRIBUTE_UNSEQUENCED __attribute__((const))
+   Remove this macro and its uses when the bug is fixed in a GCC release,
-# else
+   because only the latest GCC matters for $(GCC_DEBUG_FLAGS).  */
-#  define ATTRIBUTE_UNSEQUENCED /* empty */
+#ifdef GCC_LINT
-# endif
+# define ATTRIBUTE_PURE_114833 ATTRIBUTE_PURE
+#else
+# define ATTRIBUTE_PURE_114833 /* empty */
 #endif
 
 #if (__STDC_VERSION__ < 199901 && !defined restrict \
@@ -604,12 +623,8 @@ typedef time_tz tz_time_t;
 
 # undef  asctime
 # define asctime tz_asctime
-# undef  asctime_r
-# define asctime_r tz_asctime_r
 # undef  ctime
 # define ctime tz_ctime
-# undef  ctime_r
-# define ctime_r tz_ctime_r
 # undef  difftime
 # define difftime tz_difftime
 # undef  gmtime
@@ -654,6 +669,12 @@ typedef time_tz tz_time_t;
 # define tzfree tz_tzfree
 # undef  tzset
 # define tzset tz_tzset
+# if SUPPORT_POSIX2008
+#  undef  asctime_r
+#  define asctime_r tz_asctime_r
+#  undef  ctime_r
+#  define ctime_r tz_ctime_r
+# endif
 # if HAVE_STRFTIME_L
 #  undef  strftime_l
 #  define strftime_l tz_strftime_l
@@ -679,10 +700,12 @@ typedef time_tz tz_time_t;
 #  define DEPRECATED_IN_C23 ATTRIBUTE_DEPRECATED
 # endif
 DEPRECATED_IN_C23 char *asctime(struct tm const *);
-char *asctime_r(struct tm const *restrict, char *restrict);
 DEPRECATED_IN_C23 char *ctime(time_t const *);
+#if SUPPORT_POSIX2008
+char *asctime_r(struct tm const *restrict, char *restrict);
 char *ctime_r(time_t const *, char *);
-ATTRIBUTE_UNSEQUENCED double difftime(time_t, time_t);
+#endif
+double difftime(time_t, time_t);
 size_t strftime(char *restrict, size_t, char const *restrict,
 		struct tm const *restrict);
 # if HAVE_STRFTIME_L
@@ -713,7 +736,7 @@ void tzset(void);
 time_t timegm(struct tm *);
 #endif
 
-#if !HAVE_DECL_ASCTIME_R && !defined asctime_r
+#if !HAVE_DECL_ASCTIME_R && !defined asctime_r && SUPPORT_POSIX2008
 extern char *asctime_r(struct tm const *restrict, char *restrict);
 #endif
 
@@ -798,10 +821,10 @@ timezone_t tzalloc(char const *);
 void tzfree(timezone_t);
 # if STD_INSPIRED
 #  if TZ_TIME_T || !defined posix2time_z
-ATTRIBUTE_REPRODUCIBLE time_t posix2time_z(timezone_t, time_t);
+ATTRIBUTE_PURE time_t posix2time_z(timezone_t, time_t);
 #  endif
 #  if TZ_TIME_T || !defined time2posix_z
-ATTRIBUTE_REPRODUCIBLE time_t time2posix_z(timezone_t, time_t);
+ATTRIBUTE_PURE time_t time2posix_z(timezone_t, time_t);
 #  endif
 # endif
 #endif
@@ -973,8 +996,9 @@ enum {
 
 /* How many years to generate (in zic.c) or search through (in localtime.c).
    This is two years larger than the obvious 400, to avoid edge cases.
-   E.g., suppose a non-POSIX.1-2017 rule applies from 2012 on with transitions
+   E.g., suppose a rule applies from 2012 on with transitions
-   in March and September, plus one-off transitions in November 2013.
+   in March and September, plus one-off transitions in November 2013,
+   and suppose the rule cannot be expressed as a proleptic TZ string.
    If zic looked only at the last 400 years, it would set max_year=2413,
    with the intent that the 400 years 2014 through 2413 will be repeated.
    The last transition listed in the tzfile would be in 2413-09,

theory.html

@@ -89,13 +89,15 @@ The <code><abbr>tz</abbr></code> code is upwards compatible with <a
 href="https://en.wikipedia.org/wiki/POSIX">POSIX</a>, an international
 standard for <a
 href="https://en.wikipedia.org/wiki/Unix">UNIX</a>-like systems.
-As of this writing, the current edition of POSIX is: <a
+As of this writing, the current edition of POSIX is POSIX.1-2024,
+which has been published but not yet in HTML form.
+Unlike its predecessor POSIX.1-2017 (<a
 href="https://pubs.opengroup.org/onlinepubs/9699919799/"> The Open
 Group Base Specifications Issue 7</a>, IEEE Std 1003.1-2017, 2018
-Edition.
+Edition), POSIX.1-2024 requires support for the
-Because the database's scope encompasses real-world changes to civil
+<code><abbr>tz</abbr></code> database, which has a
-timekeeping, its model for describing time is more complex than the
+model for describing civil time that is more complex than the
-standard and daylight saving times supported by POSIX.1-2017.
+standard and daylight saving times required by POSIX.1-2017.
 A <code><abbr>tz</abbr></code> timezone corresponds to a ruleset that can
 have more than two changes per year, these changes need not merely
 flip back and forth between two alternatives, and the rules themselves
@@ -159,7 +161,7 @@ among the following goals:
 </ul>
 
 <p>
-Names normally have the form
+Names normally have the format
 <var>AREA</var><code>/</code><var>LOCATION</var>, where
 <var>AREA</var> is a continent or ocean, and
 <var>LOCATION</var> is a specific location within the area.
@@ -187,7 +189,7 @@ in decreasing order of importance:
     href="https://en.wikipedia.org/wiki/ASCII">ASCII</a> letters,
     '<code>.</code>', '<code>-</code>' and '<code>_</code>'.
     Do not use digits, as that might create an ambiguity with <a
-    href="https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap08.html#tag_08_03">POSIX.1-2017
+    href="https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap08.html#tag_08_03">POSIX's proleptic
     <code>TZ</code> strings</a>.
     A file name component must not exceed 14 characters or start with
     '<code>-</code>'.
@@ -378,7 +380,8 @@ nowadays distributions typically use it
 and no great weight should be attached to whether a link
 is defined in <code>backward</code> or in some other file.
 The source file <code>etcetera</code> defines names that may be useful
-on platforms that do not support POSIX.1-2017-style <code>TZ</code> strings;
+on platforms that do not support proleptic <code>TZ</code> strings
+like <code>&lt;+08&gt;-8</code>;
 no other source file other than <code>backward</code>
 contains links to its zones.
 One of <code>etcetera</code>'s names is <code>Etc/UTC</code>,
@@ -425,8 +428,8 @@ in decreasing order of importance:
     In other words, in the C locale the POSIX extended regular
     expression <code>[-+[:alnum:]]{3,6}</code> should match the
     abbreviation.
-    This guarantees that all abbreviations could have been specified by a
+    This guarantees that all abbreviations could have been specified
-    POSIX.1-2017 <code>TZ</code> string.
+    explicitly by a POSIX proleptic <code>TZ</code> string.
     </p>
   </li>
   <li>
@@ -578,6 +581,11 @@ in decreasing order of importance:
     some sense undefined; this notation is derived
     from <a href="https://datatracker.ietf.org/doc/html/rfc3339">Internet
     <abbr title="Request For Comments">RFC</abbr> 3339</a>.
+    (The abbreviation 'Z' that
+    <a href="https://datatracker.ietf.org/doc/html/rfc9557">Internet
+    <abbr>RFC</abbr> 9557</a> uses for this concept
+    would violate the POSIX requirement
+    of at least three characters in an abbreviation.)
   </li>
 </ul>
 
@@ -775,7 +783,7 @@ href="https://www.dissentmagazine.org/blog/booked-a-global-history-of-time-vanes
     the Western 06:00 to be 12:00. These practices are largely outside
     the scope of the <code><abbr>tz</abbr></code> code and data, which
     provide only limited support for date and time localization
-    such as that required by POSIX.1-2017.
+    such as that required by POSIX.
     If <abbr>DST</abbr> is not used a different time zone
     can often do the trick; for example, in Kenya a <code>TZ</code> setting
     like <code>&lt;-03&gt;3</code> or <code>America/Cayenne</code> starts
@@ -866,29 +874,62 @@ Code compatible with this package is already
 <a href="tz-link.html#tzdb">part of many platforms</a>, where the
 primary use of this package is to update obsolete time-related files.
 To do this, you may need to compile the time zone compiler
-'<code>zic</code>' supplied with this package instead of using the
+<code>zic</code> supplied with this package instead of using the
-system '<code>zic</code>', since the format of <code>zic</code>'s
+system <code>zic</code>, since the format of <code>zic</code>'s
 input is occasionally extended, and a platform may still be shipping
 an older <code>zic</code>.
 </p>
 
-<h3 id="POSIX">POSIX.1-2017 properties and limitations</h3>
+<p>
+In POSIX, time display in a process is controlled by the
+environment variable <code>TZ</code>, which can have two forms:
+</p>
 <ul>
+  <li>
+    A <dfn>proleptic <code>TZ</code></dfn> value
+    like <code>CET-1CEST,M3.5.0,M10.5.0/3</code> uses a complex
+    notation that specifies a single standard time along with daylight
+    saving rules that apply to all years past, present, and future.
+  </li>
+  <li>
+    A <dfn>geographical <code>TZ</code></dfn> value
+    like <code>Europe/Berlin</code> names a location that stands for
+    civil time near that location, which can have more than
+    one standard time and more than one set of daylight saving rules,
+    to record timekeeping practice more accurately.
+    These names are defined by the <code><abbr>tz</abbr></code> database.
+  </li>
+</ul>
+
+<h3 id="POSIX.1-2017">POSIX.1-2017 properties and limitations</h3>
+<p>
+Some platforms support only the features required by POSIX.1-2017,
+and have not yet upgraded to POSIX.1-2024.
+Code intended to be portable to these platforms must deal
+with problems that were fixed in later POSIX editions.
+</p>
+
+<ul>
+  <li>
+    POSIX.1-2017 does not require support for geographical <code>TZ</code>,
+    and there is no convenient and efficient way to determine
+    the <abbr>UT</abbr> offset and time zone abbreviation of arbitrary
+    timestamps, particularly for timezones
+    that do not fit into the POSIX model.
+  </li>
   <li>
     <p>
-    In POSIX.1-2017, time display in a process is controlled by the
+    The proleptic <code>TZ</code> string,
-    environment variable <code>TZ</code>.
+    which is all that POSIX.1-2017 requires,
-    Unfortunately, the POSIX.1-2017
+    has a format that is hard to describe and is error-prone in practice.
-    <code>TZ</code> string takes a form that is hard to describe and
+    Also, proleptic <code>TZ</code> strings cannot deal with daylight
-    is error-prone in practice.
-    Also, POSIX.1-2017 <code>TZ</code> strings cannot deal with daylight
     saving time rules not based on the Gregorian calendar (as in
     Morocco), or with situations where more than two time zone
     abbreviations or <abbr>UT</abbr> offsets are used in an area.
     </p>
 
     <p>
-    The POSIX.1-2017 <code>TZ</code> string takes the following form:
+    A proleptic <code>TZ</code> string has the following format:
     </p>
 
     <p>
@@ -955,7 +996,7 @@ an older <code>zic</code>.
     </dl>
 
     <p>
-    Here is an example POSIX.1-2017 <code>TZ</code> string for New
+    Here is an example proleptic <code>TZ</code> string for New
     Zealand after 2007.
     It says that standard time (<abbr>NZST</abbr>) is 12 hours ahead
     of <abbr>UT</abbr>, and that daylight saving time
@@ -966,26 +1007,46 @@ an older <code>zic</code>.
     <pre><code>TZ='NZST-12NZDT,M9.5.0,M4.1.0/3'</code></pre>
 
     <p>
-    This POSIX.1-2017 <code>TZ</code> string is hard to remember, and
+    This proleptic <code>TZ</code> string is hard to remember, and
     mishandles some timestamps before 2008.
-    With this package you can use this instead:
+    With this package you can use a geographical <code>TZ</code> instead:
     </p>
 
     <pre><code>TZ='Pacific/Auckland'</code></pre>
   </li>
+</ul>
+
+<p>
+POSIX.1-2017 also has the limitations of POSIX.1-2024,
+discussed in the next section.
+</p>
+
+<h3 id="POSIX.1-2024">POSIX.1-2024 properties and limitations</h3>
+<p>
+POSIX.1-2024 extends POSIX.1-2017 in the following significant ways:
+</p>
+<ul>
   <li>
-    POSIX does not define the <abbr>DST</abbr> transitions
+    POSIX.1-2024 requires support for geographical <code>TZ</code>.
-    for <code>TZ</code> values like
+    Earlier POSIX editions require support only for proleptic <code>TZ</code>.
-    "<code>EST5EDT</code>".
-    Traditionally the current <abbr>US</abbr> <abbr>DST</abbr> rules
-    were used to interpret such values, but this meant that the
-    <abbr>US</abbr> <abbr>DST</abbr> rules were compiled into each
-    time conversion package, and when
-    <abbr>US</abbr> time conversion rules changed (as in the United
-    States in 1987 and again in 2007), all packages that
-    interpreted <code>TZ</code> values had to be updated
-    to ensure proper results.
   </li>
+  <li>
+    POSIX.1-2024 requires <code>struct tm</code>
+    to have a <abbr>UT</abbr> offset member <code>tm_gmtoff</code>
+    and a time zone abbreviation member <code>tm_zone</code>.
+    Earlier POSIX editions lack this requirement.
+  </li>
+  <li>
+    DST transition times can range from &minus;167:59:59
+    to 167:59:59 instead of merely from 00:00:00 to 24:59:59.
+    This allows for proleptic TZ strings
+    like <code>"&lt;-02&gt;2&lt;-01&gt;,M3.5.0/-1,M10.5.0/0"</code>
+    where the transition time &minus;1:00 means 23:00 the previous day.
+  </li>
+</ul>
+<p>
+However POSIX.1-2024, like earlier POSIX editions, has some limitations:
+<ul>
   <li>
     The <code>TZ</code> environment variable is process-global, which
     makes it hard to write efficient, thread-safe applications that
@@ -1003,16 +1064,34 @@ an older <code>zic</code>.
     handling daylight saving time shifts &ndash; as might be required to
     limit phone calls to off-peak hours.
   </li>
-  <li>
-    POSIX.1-2017 provides no convenient and efficient way to determine
-    the <abbr>UT</abbr> offset and time zone abbreviation of arbitrary
-    timestamps, particularly for timezones
-    that do not fit into the POSIX model.
-  </li>
   <li>
     POSIX requires that <code>time_t</code> clock counts exclude leap
     seconds.
   </li>
+  <li>
+    POSIX does not define the <abbr>DST</abbr> transitions
+    for <code>TZ</code> values like
+    "<code>EST5EDT</code>".
+    Traditionally the current <abbr>US</abbr> <abbr>DST</abbr> rules
+    were used to interpret such values, but this meant that the
+    <abbr>US</abbr> <abbr>DST</abbr> rules were compiled into each
+    time conversion package, and when
+    <abbr>US</abbr> time conversion rules changed (as in the United
+    States in 1987 and again in 2007), all packages that
+    interpreted <code>TZ</code> values had to be updated
+    to ensure proper results.
+  </li>
+</ul>
+
+<h3 id="POSIX-extensions">Extensions to POSIX in the
+<code><abbr>tz</abbr></code> code</h3>
+<p>
+  The <code><abbr>tz</abbr></code> code defines some properties
+  left unspecified by POSIX, and attempts to support some
+  extensions to POSIX.
+</p>
+
+<ul>
   <li>
     The <code><abbr>tz</abbr></code> code attempts to support all the
     <code>time_t</code> implementations allowed by POSIX.
@@ -1026,21 +1105,14 @@ an older <code>zic</code>.
     and 40-bit integers are also used occasionally.
     Although earlier POSIX versions allowed <code>time_t</code> to be a
     floating-point type, this was not supported by any practical system,
-    and POSIX.1-2013 and the <code><abbr>tz</abbr></code> code both
+    and POSIX.1-2013+ and the <code><abbr>tz</abbr></code> code both
     require <code>time_t</code> to be an integer type.
   </li>
-</ul>
-
-<h3 id="POSIX-extensions">Extensions to POSIX.1-2017 in the
-<code><abbr>tz</abbr></code> code</h3>
-<ul>
   <li>
     <p>
-    The <code>TZ</code> environment variable is used in generating
+    If the <code>TZ</code> environment variable uses the geographical format,
-    the name of a file from which time-related information is read
+    it is used in generating
-    (or is interpreted à la POSIX.1-2017); <code>TZ</code> is no longer
+    the name of a file from which time-related information is read.
-    constrained to be a string containing abbreviations
-    and numeric data as described <a href="#POSIX">above</a>.
     The file's format is <dfn><abbr>TZif</abbr></dfn>,
     a timezone information format that contains binary data; see
     <a href="https://datatracker.ietf.org/doc/html/8536">Internet
@@ -1053,10 +1125,11 @@ an older <code>zic</code>.
     abbreviations are used.
     </p>
     <p>
-    It was recognized that allowing the <code>TZ</code> environment
+    When the <code><abbr>tz</abbr></code> code was developed in the 1980s,
+    it was recognized that allowing the <code>TZ</code> environment
     variable to take on values such as '<code>America/New_York</code>'
     might cause "old" programs (that expect <code>TZ</code> to have a
-    certain form) to operate incorrectly; consideration was given to using
+    certain format) to operate incorrectly; consideration was given to using
     some other environment variable (for example, <code>TIMEZONE</code>)
     to hold the string used to generate the <abbr>TZif</abbr> file's name.
     In the end, however, it was decided to continue using
@@ -1069,15 +1142,6 @@ an older <code>zic</code>.
     assume pre-POSIX <code>TZ</code> values.
     </p>
   </li>
-  <li>
-    The code supports platforms with a <abbr>UT</abbr> offset member
-    in <code>struct tm</code>, e.g., <code>tm_gmtoff</code>,
-    or with a time zone abbreviation member in
-    <code>struct tm</code>, e.g., <code>tm_zone</code>. As noted
-    in <a href="https://austingroupbugs.net/view.php?id=1533">Austin
-    Group defect 1533</a>, a future version of POSIX is planned to
-    require <code>tm_gmtoff</code> and <code>tm_zone</code>.
-  </li>
   <li>
     Functions <code>tzalloc</code>, <code>tzfree</code>,
     <code>localtime_rz</code>, and <code>mktime_z</code> for
@@ -1088,7 +1152,7 @@ an older <code>zic</code>.
     and <code>localtime_rz</code> and <code>mktime_z</code> are
     like <code>localtime_r</code> and <code>mktime</code> with an
     extra <code>timezone_t</code> argument.
-    The functions were inspired by <a href="https://netbsd.org/">NetBSD</a>.
+    The functions were inspired by <a href="https://netbsd.org">NetBSD</a>.
   </li>
   <li>
     Negative <code>time_t</code> values are supported, on systems
@@ -1116,6 +1180,7 @@ The vestigial <abbr>API</abbr>s are:
   <li>
     The POSIX <code>tzname</code> variable does not suffice and is no
     longer needed.
+    It is planned to be removed in a future edition of POSIX.
     To get a timestamp's time zone abbreviation, consult
     the <code>tm_zone</code> member if available; otherwise,
     use <code>strftime</code>'s <code>"%Z"</code> conversion
@@ -1124,6 +1189,7 @@ The vestigial <abbr>API</abbr>s are:
   <li>
     The POSIX <code>daylight</code> and <code>timezone</code>
     variables do not suffice and are no longer needed.
+    They are planned to be removed in a future edition of POSIX.
     To get a timestamp's <abbr>UT</abbr> offset, consult
     the <code>tm_gmtoff</code> member if available; otherwise,
     subtract values returned by <code>localtime</code>
@@ -1278,13 +1344,13 @@ between now and the future time.
 <p>
 Leap seconds were introduced in 1972 to accommodate the
 difference between atomic time and the less regular rotation of the earth.
-Unfortunately they caused so many problems with civil
+Unfortunately they have caused so many problems with civil
-timekeeping that they
+timekeeping that there are
-are <a href="https://www.bipm.org/en/cgpm-2022/resolution-4">planned
+<a href="https://www.bipm.org/en/cgpm-2022/resolution-4">plans
-to be discontinued by 2035</a>, with some as-yet-undetermined
+to discontinue them by 2035</a>.
-mechanism replacing them, perhaps after the year 2135.
+Even if these plans come to fruition, a record of leap seconds will still be
-Despite their impending obsolescence, a record of leap seconds is still
+needed to resolve timestamps from 1972 through 2035,
-needed to resolve timestamps from 1972 through 2035.
+and there may also be a need to record whatever mechanism replaces them.
 </p>
 
 <p>
@@ -1374,6 +1440,12 @@ href='https://www.esa.int/Applications/Navigation/Telling_time_on_the_Moon'>cons
 the establishment of a reference timescale for the Moon, which has
 days roughly equivalent to 29.5 Earth days, and where relativistic
 effects cause clocks to tick slightly faster than on Earth.
+Also, <abbr title="National Aeronautics and Space Administration">NASA</abbr>
+has been <a
+href='https://www.whitehouse.gov/wp-content/uploads/2024/04/Celestial-Time-Standardization-Policy.pdf'>ordered</a>
+to consider the establishment of Coordinated Lunar Time (<abbr>LTC</abbr>).
+It is not yet known whether the US and European efforts will result in
+multiple timescales on the Moon.
 </p>
 
 <p>

tz-art.html

@@ -228,6 +228,11 @@ of the 1999-11 <em>Atlantic Monthly</em>.
 magazine's 2002-11-11 issue; among other things, it proposed
 year-round <abbr>DST</abbr> as a way of lessening wintertime despair.
 </li>
+<li>
+Cory Doctorow, <a
+href="https://craphound.com/est/download/"><em>Eastern Standard Tribe</em></a>,
+2004. The world splinters into tribes characterized by their timezones.
+</li>
 </ul>
 <h2>Music</h2>
 <ul>

tz-link.html

@@ -81,10 +81,11 @@ C Library</a> (used in
 title="Berkeley Software Distribution">BSD</abbr></a>,
 <a href="https://netbsd.org">Net<abbr>BSD</abbr></a>,
 <a href="https://www.openbsd.org">Open<abbr>BSD</abbr></a>,
-<a href="https://www.chromium.org/chromium-os/">Chromium OS</a>,
+<a href="https://www.chromium.org/chromium-os/">ChromiumOS</a>,
 <a href="https://cygwin.com">Cygwin</a>,
 <a href="https://mariadb.org">MariaDB</a>,
 <a href="https://en.wikipedia.org/wiki/MINIX">MINIX</a>,
+<a href="https://musl.libc.org">musl libc</a>,
 <a href="https://www.mysql.com">MySQL</a>,
 <a href="https://en.wikipedia.org/wiki/WebOS"><abbr
 title="Web Operating System">webOS</abbr></a>,
@@ -112,9 +113,9 @@ eastern time but with different <abbr>DST</abbr> rules in 1975;
 and other entries represent smaller regions like Starke County,
 Indiana, which switched from central to eastern time in 1991
 and switched back in 2006.
-To use the database on an extended <a
+To use the database on a <a
 href="https://en.wikipedia.org/wiki/POSIX"><abbr
-title="Portable Operating System Interface">POSIX</abbr>.1-2017</a>
+title="Portable Operating System Interface">POSIX</abbr>.1-2024</a>
 implementation set the <code><abbr>TZ</abbr></code>
 environment variable to the location's full name,
 e.g., <code><abbr>TZ</abbr>="America/New_York"</code>.</p>
@@ -192,9 +193,10 @@ After obtaining the code and data files, see the
 <code>README</code> file for what to do next.
 The code lets you compile the <code><abbr>tz</abbr></code> source files into
 machine-readable binary files, one for each location. The binary files
-are in a special timezone information format (<dfn><abbr>TZif</abbr></dfn>)
+are in a special format specified by
-specified by <a href="https://datatracker.ietf.org/doc/html/8536">Internet
+<a href="https://datatracker.ietf.org/doc/html/8536">The
-<abbr>RFC</abbr> 8536</a>.
+Time Zone Information Format (<abbr>TZif</abbr>)</a>
+(Internet <abbr title="Request For Comments">RFC</abbr> 8536).
 The code also lets
 you read a <abbr>TZif</abbr> file and interpret timestamps for that
 location.</p>
@@ -205,13 +207,11 @@ location.</p>
 <p>
 The <code><abbr>tz</abbr></code> code and data
 are by no means authoritative. If you find errors, please
-send changes to <a href="mailto:tz@iana.org"><code>tz@iana.org</code></a>,
+email changes to <a href="mailto:tz@iana.org"><code>tz@iana.org</code></a>,
-the time zone mailing list. You can also <a
+the time zone mailing list. See
-href="https://mm.icann.org/mailman/listinfo/tz">subscribe</a> to it
+<a href="https://lists.iana.org/postorius/lists/tz.iana.org/">the mailing
-and browse the <a
+list's main page</a> to subscribe or to browse its archive of old messages.
-href="https://mm.icann.org/pipermail/tz/">archive of old
+<a href="https://tzdata-meta.timtimeonline.com">Metadata for mailing list
-messages</a>.
-<a href="https://tzdata-meta.timtimeonline.com/">Metadata for mailing list
 discussions</a> and corresponding data changes can be
 generated <a href="https://github.com/timparenti/tzdata-meta">automatically</a>.
 </p>
@@ -226,7 +226,7 @@ the process by tailoring the generic instructions in
 the <code><abbr>tz</abbr> README</code> file and installing the latest
 data yourself. System-specific instructions for installing the
 latest <code><abbr>tz</abbr></code> data have also been published
-for <a href="https://developer.ibm.com/articles/au-aix-olson-time-zone/"><abbr>AIX</abbr></a>,
+for <a href="https://www.ibm.com/support/pages/aix-time-zone-olson-tzdata-updates"><abbr>AIX</abbr></a>,
 <a
 href="https://source.android.com/devices/tech/config/timezone-rules">Android</a>,
 <a
@@ -248,7 +248,7 @@ with lines terminated by <a href="https://en.wikipedia.org/wiki/Newline"><abbr
 title="linefeed">LF</abbr></a>,
 which can be modified by common text editors such
 as <a href="https://www.gnu.org/software/emacs/">GNU Emacs</a>,
-<a href="https://wiki.gnome.org/Apps/Gedit">gedit</a>, and
+<a href="https://gedit-technology.github.io/apps/gedit/">gedit</a>, and
 <a href="https://www.vim.org">vim</a>.
 Specialized source-file editing can be done via the
 <a href="https://packagecontrol.io/packages/zoneinfo">Sublime
@@ -261,8 +261,8 @@ Studio Code</a>.
 <p>
 For further information about updates, please see
 <a href="https://datatracker.ietf.org/doc/html/rfc6557">Procedures for
-Maintaining the Time Zone Database</a> (Internet <abbr
+Maintaining the Time Zone Database</a> (Internet <abbr>RFC</abbr> 6557).
-title="Request For Comments">RFC</abbr> 6557). More detail can be
+More detail can be
 found in <a href="theory.html">Theory and pragmatics of the
 <code><abbr>tz</abbr></code> code and data</a>.
 <a href="https://a0.github.io/a0-tzmigration/">A0 TimeZone Migration</a>
@@ -400,7 +400,7 @@ variant <a href="https://datatracker.ietf.org/doc/html/rfc6321">xCal</a>
 title="Extensible Markup Language">XML</abbr></a> format, and a variant
 <a href="https://datatracker.ietf.org/doc/html/rfc7265">jCal</a>
 (Internet <abbr>RFC</abbr> 7265)
-uses <a href="https://www.json.org"><abbr
+uses <a href="https://www.json.org/json-en.html"><abbr
 title="JavaScript Object Notation">JSON</abbr></a> format.</li>
 </ul>
 </section>
@@ -413,7 +413,7 @@ distributions you can generally work around compatibility problems by
 running the command <code>make rearguard_tarballs</code> and compiling
 from the resulting tarballs instead.</p>
 <ul>
-<li><a href="https://sourceforge.net/projects/vzic/">Vzic</a> is a <a
+<li><a href="https://github.com/libical/vzic">Vzic</a> is a <a
 href="https://en.wikipedia.org/wiki/C_(programming_language)">C</a>
 program that compiles
 <code><abbr>tz</abbr></code> source into iCalendar-compatible VTIMEZONE files.
@@ -440,11 +440,9 @@ transition in the <code><abbr>tz</abbr></code> database.</li>
 <li>The <a href="https://howardhinnant.github.io/date/tz.html">Time Zone
 Database Parser</a> is a
 <a href="https://en.wikipedia.org/wiki/C++">C++</a> parser and
-runtime library with <a
+runtime library with a <a
-href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0355r7.html">API</a>
+href="https://en.cppreference.com/w/cpp/chrono"><code>std::chrono</code> API</a>
-adopted by
+that is a standard part of C++.
-<a href="https://en.wikipedia.org/wiki/C++20">C++20</a>,
-the current iteration of the C++ standard.
 It is freely available under the
 <abbr title="Massachusetts Institute of Technology">MIT</abbr> license.</li>
 <li><a id="ICU" href="https://icu.unicode.org">International Components for
@@ -467,8 +465,8 @@ freely available under the <abbr>MIT</abbr> license.</li>
 <li>The <a
 href="https://www.oracle.com/java/technologies/javase/tzupdater-readme.html">TZUpdater
 tool</a> compiles <code><abbr>tz</abbr></code> source into the format used by
-<a href="https://openjdk.java.net/">OpenJDK</a> and
+<a href="https://openjdk.org">OpenJDK</a> and
-<a href="https://jdk.java.net/">Oracle JDK</a>.
+<a href="https://jdk.java.net">Oracle JDK</a>.
 Although its source code is proprietary, its executable is available under the
 <a href="https://www.oracle.com/a/tech/docs/tzupdater-lic.html">Java SE
 Timezone Updater License Agreement</a>.</li>
@@ -490,7 +488,7 @@ are alternatives to TZUpdater. IANA Updater's license is unclear;
 ZIUpdater is licensed under the <abbr>GPL</abbr>.</li>
 <li><a href="https://github.com/MenoData/Time4A">Time4A: Advanced date and
 time library for Android</a> and
-<a href="https://github.com/MenoData/Time4J/">Time4J: Advanced date,
+<a href="https://github.com/MenoData/Time4J">Time4J: Advanced date,
 time and interval library for Java</a> compile
 <code><abbr>tz</abbr></code> source into a binary format.
 Time4A is available under the Apache License and Time4J is
@@ -516,7 +514,7 @@ many of which also support runtimes lacking the <code>timeZone</code> option.
 href="https://github.com/formatjs/date-time-format-timezone"><code>Intl.DateTimeFormat</code>
 timezone polyfill</a>
 is freely available under a <abbr>BSD</abbr>-style license.</li>
-<li>The <a href="https://date-fns.org/">date-fns</a>
+<li>The <a href="https://date-fns.org">date-fns</a>
 library manipulates timezone-aware timestamps in browsers and
 in <a href="https://nodejs.org/en/">Node.js</a>.
 It is freely available under the <abbr>MIT</abbr> license.</li>
@@ -552,9 +550,9 @@ objects</a> let programs access an abstract view of
 <code><abbr>tzdb</abbr></code> data, and are designed to replace <a
 href="https://codeofmatt.com/javascript-date-type-is-horribly-broken/">JavaScript's
 problematic <code>Date</code> objects</a> when working with dates and times.
-<li><a href="https://github.com/JuliaTime/">JuliaTime</a> contains a
+<li><a href="https://github.com/JuliaTime">JuliaTime</a> contains a
 compiler from <code><abbr>tz</abbr></code> source into
-<a href="https://julialang.org/">Julia</a>. It is freely available
+<a href="https://julialang.org">Julia</a>. It is freely available
 under the <abbr>MIT</abbr> license.</li>
 <li><a href="https://github.com/pavkam/tzdb"><abbr>TZDB</abbr> &ndash;
 <abbr>IANA</abbr> Time Zone Database for Delphi/<abbr
@@ -565,7 +563,7 @@ as compiled by <a href="https://en.wikipedia.org/wiki/Delphi_(IDE)">Delphi</a>
 and <a
 href="https://en.wikipedia.org/wiki/Free_Pascal"><abbr>FPC</abbr></a>.
 It is freely available under a <abbr>BSD</abbr>-style license.</li>
-<li><a href="http://pytz.sourceforge.net">pytz &ndash; World Timezone
+<li><a href="https://pythonhosted.org/pytz/">pytz &ndash; World Timezone
 Definitions for Python</a> compiles <code><abbr>tz</abbr></code> source into
 <a href="https://www.python.org">Python</a>.
 It is freely available under a <abbr>BSD</abbr>-style license.
@@ -621,11 +619,11 @@ License.</li>
 <a href="https://github.com/nayarsystems/posix_tz_db"><code>posix_tz_db</code>
 package</a> contains Python code
 to generate <abbr>CSV</abbr> and <abbr>JSON</abbr> tables that map
-<code><abbr>tz</abbr></code> settings to POSIX.1-2017-like approximations.
+<code><abbr>tz</abbr></code> settings to proleptic TZ approximations.
 For example, it maps <code>"Africa/Cairo"</code>
 to <code>"EET-2EEST,M4.5.5/0,M10.5.4/24"</code>,
 an approximation valid for Cairo timestamps from 2023 on.
-This can help porting to platforms that support only POSIX.1-2017.
+This can help porting to platforms that support only proleptic TZ.
 The package is freely available under the MIT license.</li>
 <li><a href="https://github.com/derickr/timelib">Timelib</a> is a C
 library that reads <abbr>TZif</abbr> files and converts
@@ -649,7 +647,7 @@ that represent <code><abbr>tzdb</abbr></code> timezones.
 Python is freely available under the
 <a href="https://docs.python.org/3/license.html">Python Software Foundation
 License</a>.
-A companion <a id="pypi-tzdata" href="https://pypi.org/">PyPI</a> module
+A companion <a id="pypi-tzdata" href="https://pypi.org">PyPI</a> module
 <a href="https://pypi.org/project/tzdata/"><code>tzdata</code></a>
 supplies TZif data if the underlying system data cannot be found;
 it is freely available under the Apache License.</li>
@@ -897,9 +895,10 @@ summarizes and cites historical <abbr>DST</abbr> regulations.</dd>
 href="https://www.ptb.de/cms/en/fachabteilungen/abt4/fb-44/ag-441/realisation-of-legal-time-in-germany.html">Realisation
 of Legal Time in Germany</a>.</dd>
 <dt>Israel</dt>
-<dd>The Interior Ministry periodically issues <a
+<dd><a
-href="ftp://ftp.cs.huji.ac.il/pub/tz/announcements"
+href="https://tz.cs.huji.ac.il">Israel Timezone Files</a>
-hreflang="he">announcements (in Hebrew)</a>.</dd>
+lists official time-change announcements and laws since 1940,
+almost all in Hebrew.</dd>
 <dt>Malaysia</dt>
 <dd>See Singapore <a href="#Singapore">below</a>.</dd>
 <dt>Mexico</dt>
@@ -1081,6 +1080,20 @@ In practice the two configurations also agree for timestamps before
 1972 even though the historical situation is messy, partly because
 neither <abbr>UTC</abbr> nor <abbr>TAI</abbr>
 is well-defined for sufficiently old timestamps.</li>
+<li><a href="https://kb.meinbergglobal.com/kb/time_sync/ntp/configuration/ntp_leap_second_file">The
+<abbr>NTP</abbr> Leap Second File</a> covers the text file
+<code>leap-seconds.list</code>, which lists the currently known leap seconds.
+The <abbr>IERS</abbr> maintains this file, and a copy is distributed by
+<code><abbr>tzdb</abbr></code> for use by <abbr>NTP</abbr> implementations like
+<a href="https://www.ntp.org">classic
+<code><abbr title="Network Time Protocol Daemon">ntpd</abbr></code></a>
+and <a href="https://ntpsec.org">NTPsec</a>.
+The <code><abbr>tz</abbr></code> database also distributes leap second
+information in a differently-formatted <code>leapseconds</code> text file,
+as well as in the "<code>right</code>" configuration in binary form; for
+example, <code>right/UTC</code> can be used
+by <a href="https://chrony-project.org"><code>chrony</code></a>,
+another <abbr>NTP</abbr> implementation.</li>
 <li><a href="https://developers.google.com/time/smear">Leap Smear</a>
 discusses how to gradually adjust <abbr>POSIX</abbr> clocks near a
 leap second so that they disagree with <abbr>UTC</abbr> by at most a
@@ -1088,7 +1101,7 @@ half second, even though every <abbr>POSIX</abbr> minute has exactly
 sixty seconds. This approach works with the default <code><abbr>tz</abbr></code>
 "<code>posix</code>" configuration, is <a
 href="http://bk1.ntp.org/ntp-stable/README.leapsmear">supported</a> by
-the <abbr>NTP</abbr> reference implementation, <a
+the abovementioned <abbr>NTP</abbr> implementations, <a
 href="https://github.com/google/unsmear">supports</a> conversion between
 <abbr>UTC</abbr> and smeared <abbr>POSIX</abbr> timestamps, and is used by major
 cloud service providers. However, according to
@@ -1111,11 +1124,18 @@ without Leap Seconds</a> gives pointers on this
 contentious issue.
 The General Conference on Weights and Measures
 <a href="https://www.bipm.org/en/cgpm-2022/resolution-4">decided in 2022</a>
-to discontinue the use of leap seconds by 2035, replacing them with an
+to discontinue the use of leap seconds by 2035, and requested that no
-as-yet-undetermined scheme some time after the year 2135.
+discontinuous adjustments be made to UTC for at least a century.
 The World Radiocommunication Conference <a
 href="https://www.itu.int/dms_pub/itu-r/opb/act/R-ACT-WRC.15-2023-PDF-E.pdf">resolved
 in 2023</a> to cooperate with this process.
+<a href="https://www.preprints.org/manuscript/202406.0043/v1">A proposal
+to change the leap-second adjustments to Coordinated Universal Time</a>
+(doi:<a href="https://doi.org/10.1088/1681-7575/ad6266">10.1088/1681-7575/ad6266</a>)
+would replace leap seconds with 13-second leap smears occurring once per
+decade until 2100, with leap smears after that gradually increasing in size.
+However, there is still no consensus on whether this is the best way
+to replace leap seconds.
 </li>
 </ul>
 </section>
@@ -1153,9 +1173,12 @@ headers.</li>
 <li>
 <a href="https://datatracker.ietf.org/doc/html/rfc3339">Date and Time
 on the Internet: Timestamps</a> (Internet <abbr>RFC</abbr> 3339)
-specifies an <abbr>ISO</abbr> 8601
+specifies an <abbr>ISO</abbr> 8601 profile for use in new Internet protocols.
-profile for use in new Internet
+An extension, <a href="https://datatracker.ietf.org/doc/html/rfc9557">Date
-protocols.</li>
+and Time on the Internet: Timestamps with Additional Information</a>
+(Internet <abbr>RFC</abbr> 9557) extends this profile
+to let you specify the <code><abbr>tzdb</abbr></code> timezone of a timestamp
+via suffixes like "<code>[Asia/Tokyo]</code>".
 <li>
 <a href="https://web.archive.org/web/20190130042457/https://www.hackcraft.net/web/datetime/">Date &amp; Time
 Formats on the Web</a> surveys web- and Internet-oriented date and time
@@ -1173,8 +1196,8 @@ unfortunately some of these abbreviations were merely the database maintainers'
 inventions, and these have been removed when possible.</li>
 <li>Numeric time zone abbreviations typically count hours east of
 <abbr>UT</abbr>, e.g., +09 for Japan and
-&minus;10 for Hawaii. However, the <abbr>POSIX</abbr>
+&minus;10 for Hawaii. However, <abbr>POSIX</abbr> proleptic
-<code><abbr>TZ</abbr></code> environment variable uses the opposite convention.
+<code><abbr>TZ</abbr></code> settings use the opposite convention.
 For example, one might use <code><abbr>TZ</abbr>="<abbr
 title="Japan Standard Time">JST</abbr>-9"</code> and
 <code><abbr>TZ</abbr>="<abbr title="Hawaii Standard Time">HST</abbr>10"</code>

tzfile.5

@@ -42,7 +42,7 @@ or
 Fifteen bytes containing zeros reserved for future use.
 .IP \(bu
 Six four-byte integer values, in the following order:
-.RS "\w'  \(bu    'u"
+.RS "\w'\(bu    'u"
 .TP "\w'  'u"
 .B tzh_ttisutcnt
 The number of UT/local indicators stored in the file.
@@ -66,6 +66,7 @@ in the file (must not be zero).
 The number of bytes of time zone abbreviation strings
 stored in the file.
 .RE
+.RE
 .PP
 The above header is followed by the following fields, whose lengths
 depend on the contents of the header:
@@ -85,7 +86,7 @@ described in the file is associated with the time period
 starting with the same-indexed transition time
 and continuing up to but not including the next transition time.
 (The last time type is present only for consistency checking with the
-POSIX.1-2017-style TZ string described below.)
+proleptic TZ string described below.)
 These values serve as indices into the next field.
 .IP \(bu
 .B tzh_typecnt
@@ -134,8 +135,7 @@ Also, in realistic applications
 is in the range [\-89999, 93599] (i.e., more than \-25 hours and less
 than 26 hours); this allows easy support by implementations that
 already support the POSIX-required range [\-24:59:59, 25:59:59].
-.RS "\w'  'u"
+.IP \(bu
-.IP \(bu "\w'\(bu  'u"
 .B tzh_charcnt
 bytes that represent time zone designations,
 which are null-terminated byte strings, each indexed by the
@@ -187,12 +187,12 @@ must also be set.
 The standard/wall and UT/local indicators were designed for
 transforming a TZif file's transition times into transitions appropriate
 for another time zone specified via
-a POSIX.1-2017-style TZ string that lacks rules.
+a proleptic TZ string that lacks rules.
 For example, when TZ="EET\*-2EEST" and there is no TZif file "EET\*-2EEST",
 the idea was to adapt the transition times from a TZif file with the
 well-known name "posixrules" that is present only for this purpose and
 is a copy of the file "Europe/Brussels", a file with a different UT offset.
-POSIX does not specify this obsolete transformational behavior,
+POSIX does not specify the details of this obsolete transformational behavior,
 the default rules are installation-dependent, and no implementation
 is known to support this feature for timestamps past 2037,
 so users desiring (say) Greek time should instead specify
@@ -217,12 +217,12 @@ identical in format except that
 eight bytes are used for each transition time or leap second time.
 (Leap second counts remain four bytes.)
 After the second header and data comes a newline-enclosed string
-in the style of the contents of a POSIX.1-2017 TZ environment variable,
+in the style of the contents of a proleptic TZ,
 for use in handling instants
 after the last transition time stored in the file
 or for all instants if the file has no transitions.
 The TZ string is empty (i.e., nothing between the newlines)
-if there is no POSIX.1-2017-style representation for such instants.
+if there is no proleptic representation for such instants.
 If nonempty, the TZ string must agree with the local time
 type after the last transition time if present in the eight-byte data;
 for example, given the string
@@ -235,13 +235,14 @@ Also, if there is at least one transition, time type 0 is associated
 with the time period from the indefinite past up to but not including
 the earliest transition time.
 .SS Version 3 format
-For version-3-format timezone files, the TZ string may
+For version-3-format timezone files, a TZ string (see
-use two minor extensions to the POSIX.1-2017 TZ format, as described in
+.BR newtzset (3))
-.BR newtzset (3).
+may use the following POSIX.1-2024 extensions to POSIX.1-2017:
-First, the hours part of its transition times may be signed and range from
+First, as in TZ="<\*-02>2<\*-01>,M3.5.0/\*-1,M10.5.0/0",
-\-167 through 167 instead of the POSIX-required unsigned values
+the hours part of its transition times may be signed and range from
+\-167 through 167 instead of being limited to unsigned values
 from 0 through 24.
-Second, DST is in effect all year if it starts
+Second, as in TZ="XXX3EDT4,0/0,J365/23", DST is in effect all year if it starts
 January 1 at 00:00 and ends December 31 at 24:00 plus the difference
 between daylight saving and standard time.
 .SS Version 4 format
@@ -354,7 +355,8 @@ version 2+ data even if the reader's native timestamps have only
 .IP \(bu
 Some readers designed for version 2 might mishandle
 timestamps after a version 3 or higher file's last transition, because
-they cannot parse extensions to POSIX.1-2017 in the TZ-like string.
+they cannot parse the POSIX.1-2024 extensions to POSIX.1-2017
+in the proleptic TZ string.
 As a partial workaround, a writer can output more transitions
 than necessary, so that only far-future timestamps are
 mishandled by version 2 readers.
@@ -386,6 +388,18 @@ timestamps from the time type of the last transition.
 As a partial workaround, a writer can output more transitions
 than necessary.
 .IP \(bu
+Some stripped-down readers ignore everything but the footer,
+and use its proleptic TZ string to calculate all timestamps.
+Although this approach often works for current and future timestamps,
+it obviously has problems with past timestamps,
+and even for current timestamps it can fail for settings like
+TZ="Africa/Casablanca".  This corresponds to a TZif file
+containing explicit transitions through the year 2087,
+followed by a footer containing the TZ string
+.q <+01>\*-1 ,
+which should be used only for timestamps after the last
+explicit transition.
+.IP \(bu
 Some readers do not use time type 0 for timestamps before
 the first transition, in that they infer a time type using a
 heuristic that does not always select time type 0.

tzfile.5.txt

@@ -24,276 +24,284 @@ DESCRIPTION
 
          o  Six four-byte integer values, in the following order:
 
-                tzh_ttisutcnt
+              tzh_ttisutcnt
-                  The number of UT/local indicators stored in the  file.   (UT
+                The number of UT/local indicators stored in the file.  (UT  is
-                  is Universal Time.)
+                Universal Time.)
 
-                tzh_ttisstdcnt
+              tzh_ttisstdcnt
-                  The number of standard/wall indicators stored in the file.
+                The number of standard/wall indicators stored in the file.
 
-                tzh_leapcnt
+              tzh_leapcnt
-                  The number of leap seconds for which data entries are stored
+                The  number  of leap seconds for which data entries are stored
-                  in the file.
+                in the file.
 
-                tzh_timecnt
+              tzh_timecnt
-                  The  number  of  transition times for which data entries are
+                The number of transition times  for  which  data  entries  are
-                  stored in the file.
+                stored in the file.
 
-                tzh_typecnt
+              tzh_typecnt
-                  The number of local time types for which  data  entries  are
+                The  number  of  local  time  types for which data entries are
-                  stored in the file (must not be zero).
+                stored in the file (must not be zero).
 
-                tzh_charcnt
+              tzh_charcnt
-                  The number of bytes of time zone abbreviation strings stored
+                The number of bytes of time zone abbreviation  strings  stored
-                  in the file.
+                in the file.
 
-         The  above  header is followed by the following fields, whose lengths
+       The  above  header  is  followed by the following fields, whose lengths
-         depend on the contents of the header:
+       depend on the contents of the header:
 
-           o  tzh_timecnt four-byte signed integer values sorted in  ascending
+         o  tzh_timecnt four-byte signed integer values  sorted  in  ascending
-              order.  These values are written in network byte order.  Each is
+            order.   These  values are written in network byte order.  Each is
-              used  as a transition time (as returned by time(2)) at which the
+            used as a transition time (as returned by time(2))  at  which  the
-              rules for computing local time change.
+            rules for computing local time change.
 
-           o  tzh_timecnt one-byte unsigned integer values; each one  but  the
+         o  tzh_timecnt  one-byte  unsigned  integer  values; each one but the
-              last  tells  which  of  the  different types of local time types
+            last tells which of  the  different  types  of  local  time  types
-              described in  the  file  is  associated  with  the  time  period
+            described  in the file is associated with the time period starting
-              starting with the same-indexed transition time and continuing up
+            with the same-indexed transition time and continuing up to but not
-              to  but  not including the next transition time.  (The last time
+            including the next  transition  time.   (The  last  time  type  is
-              type  is  present  only  for  consistency  checking   with   the
+            present only for consistency checking with the proleptic TZ string
-              POSIX.1-2017-style  TZ  string  described  below.)  These values
+            described  below.)   These  values  serve as indices into the next
-              serve as indices into the next field.
+            field.
 
-           o  tzh_typecnt ttinfo entries, each defined as follows:
+         o  tzh_typecnt ttinfo entries, each defined as follows:
 
-                struct ttinfo {
+              struct ttinfo {
-                    int32_t       tt_utoff;
+                  int32_t       tt_utoff;
-                    unsigned char tt_isdst;
+                  unsigned char tt_isdst;
-                    unsigned char tt_desigidx;
+                  unsigned char tt_desigidx;
-                };
+              };
 
-              Each structure is written as a four-byte  signed  integer  value
+            Each structure is written as a four-byte signed integer value  for
-              for  tt_utoff,  in  network  byte  order, followed by a one-byte
+            tt_utoff,  in  network  byte order, followed by a one-byte boolean
-              boolean for tt_isdst and a one-byte value for  tt_desigidx.   In
+            for tt_isdst and  a  one-byte  value  for  tt_desigidx.   In  each
-              each structure, tt_utoff gives the number of seconds to be added
+            structure, tt_utoff gives the number of seconds to be added to UT,
-              to  UT,  tt_isdst  tells  whether  tm_isdst  should  be  set  by
+            tt_isdst  tells whether tm_isdst should be set by localtime(3) and
-              localtime(3) and tt_desigidx serves as an index into  the  array
+            tt_desigidx serves as  an  index  into  the  array  of  time  zone
-              of  time  zone abbreviation bytes that follow the ttinfo entries
+            abbreviation  bytes that follow the ttinfo entries in the file; if
-              in the file; if the designated string is "-00", the ttinfo entry
+            the designated string is "-00", the ttinfo entry is a  placeholder
-              is a placeholder indicating that local time is unspecified.  The
+            indicating  that local time is unspecified.  The tt_utoff value is
-              tt_utoff value is never equal to -2**31, to let  32-bit  clients
+            never equal to -2**31, to let 32-bit  clients  negate  it  without
-              negate  it  without  overflow.   Also, in realistic applications
+            overflow.   Also,  in  realistic  applications  tt_utoff is in the
-              tt_utoff is in the range [-89999, 93599] (i.e.,  more  than  -25
+            range [-89999, 93599] (i.e., more than -25 hours and less than  26
-              hours  and  less  than  26  hours);  this allows easy support by
+            hours);  this  allows easy support by implementations that already
-              implementations that already support  the  POSIX-required  range
+            support the POSIX-required range [-24:59:59, 25:59:59].
-              [-24:59:59, 25:59:59].
 
-             o  tzh_charcnt bytes that represent time zone designations, which
+         o  tzh_charcnt bytes that represent time zone designations, which are
-                are   null-terminated   byte  strings,  each  indexed  by  the
+            null-terminated byte strings,  each  indexed  by  the  tt_desigidx
-                tt_desigidx values mentioned  above.   The  byte  strings  can
+            values  mentioned above.  The byte strings can overlap if one is a
-                overlap  if  one  is  a  suffix of the other.  The encoding of
+            suffix of the  other.   The  encoding  of  these  strings  is  not
-                these strings is not specified.
+            specified.
 
-             o  tzh_leapcnt pairs of four-byte values, written in network byte
+         o  tzh_leapcnt  pairs  of  four-byte  values, written in network byte
-                order; the first value of each pair gives the nonnegative time
+            order; the first value of each pair gives the nonnegative time (as
-                (as returned by time(2)) at which a leap second occurs  or  at
+            returned by time(2)) at which a leap second occurs or at which the
-                which  the  leap  second table expires; the second is a signed
+            leap  second  table  expires;  the  second  is  a  signed  integer
-                integer specifying the correction, which is the  total  number
+            specifying  the  correction,  which  is  the  total number of leap
-                of  leap seconds to be applied during the time period starting
+            seconds to be applied during the time period starting at the given
-                at the given time.  The pairs of values are sorted in strictly
+            time.  The pairs of values are sorted in strictly ascending  order
-                ascending order by time.  Each pair denotes one  leap  second,
+            by  time.   Each  pair denotes one leap second, either positive or
-                either  positive or negative, except that if the last pair has
+            negative, except that if the last pair has the same correction  as
-                the same correction as the previous one, the last pair denotes
+            the  previous  one,  the last pair denotes the leap second table's
-                the leap second table's expiration time.  Each leap second  is
+            expiration time.  Each leap second is at the end of a UTC calendar
-                at the end of a UTC calendar month.  The first leap second has
+            month.  The first leap second has a nonnegative  occurrence  time,
-                a  nonnegative  occurrence time, and is a positive leap second
+            and  is  a  positive  leap second if and only if its correction is
-                if and only if its correction is positive; the correction  for
+            positive; the correction for each  leap  second  after  the  first
-                each  leap  second  after  the first differs from the previous
+            differs  from  the previous leap second by either 1 for a positive
-                leap second by either 1 for a positive leap second, or -1  for
+            leap second, or -1 for a negative leap second.  If the leap second
-                a  negative  leap  second.  If the leap second table is empty,
+            table is  empty,  the  leap-second  correction  is  zero  for  all
-                the  leap-second  correction  is  zero  for  all   timestamps;
+            timestamps;  otherwise, for timestamps before the first occurrence
-                otherwise,  for  timestamps  before the first occurrence time,
+            time, the leap-second correction  is  zero  if  the  first  pair's
-                the  leap-second  correction  is  zero  if  the  first  pair's
+            correction  is  1  or  -1, and is unspecified otherwise (which can
-                correction is 1 or -1, and is unspecified otherwise (which can
+            happen only in files truncated at the start).
-                happen only in files truncated at the start).
 
-             o  tzh_ttisstdcnt standard/wall indicators, each stored as a one-
+         o  tzh_ttisstdcnt standard/wall indicators, each stored as a one-byte
-                byte   boolean;   they   tell  whether  the  transition  times
+            boolean; they tell whether the transition  times  associated  with
-                associated with local time types were  specified  as  standard
+            local  time  types  were specified as standard time or local (wall
-                time or local (wall clock) time.
+            clock) time.
 
-             o  tzh_ttisutcnt  UT/local  indicators, each stored as a one-byte
+         o  tzh_ttisutcnt UT/local  indicators,  each  stored  as  a  one-byte
-                boolean; they tell whether  the  transition  times  associated
+            boolean;  they  tell  whether the transition times associated with
-                with  local time types were specified as UT or local time.  If
+            local time types were  specified  as  UT  or  local  time.   If  a
-                a UT/local indicator is set, the  corresponding  standard/wall
+            UT/local   indicator   is  set,  the  corresponding  standard/wall
-                indicator must also be set.
+            indicator must also be set.
 
-           The   standard/wall  and  UT/local  indicators  were  designed  for
+       The  standard/wall  and   UT/local   indicators   were   designed   for
-           transforming  a  TZif  file's  transition  times  into  transitions
+       transforming   a   TZif   file's   transition  times  into  transitions
-           appropriate    for    another    time    zone   specified   via   a
+       appropriate for another time zone specified via a proleptic  TZ  string
-           POSIX.1-2017-style TZ string that lacks rules.  For  example,  when
+       that  lacks  rules.   For  example, when TZ="EET-2EEST" and there is no
-           TZ="EET-2EEST"  and there is no TZif file "EET-2EEST", the idea was
+       TZif file "EET-2EEST", the idea was to adapt the transition times  from
-           to adapt the transition times from a TZif file with the  well-known
+       a  TZif file with the well-known name "posixrules" that is present only
-           name  "posixrules"  that  is present only for this purpose and is a
+       for this purpose and is a copy of the file  "Europe/Brussels",  a  file
-           copy of the file "Europe/Brussels", a  file  with  a  different  UT
+       with a different UT offset.  POSIX does not specify the details of this
-           offset.   POSIX  does  not  specify  this obsolete transformational
+       obsolete transformational behavior, the default rules are installation-
-           behavior, the default  rules  are  installation-dependent,  and  no
+       dependent,  and  no implementation is known to support this feature for
-           implementation is known to support this feature for timestamps past
+       timestamps past 2037, so users desiring (say) Greek time should instead
-           2037,  so  users  desiring  (say) Greek time should instead specify
+       specify TZ="Europe/Athens" for better historical coverage, falling back
-           TZ="Europe/Athens" for better historical coverage, falling back  on
+       on TZ="EET-2EEST,M3.5.0/3,M10.5.0/4" if POSIX conformance  is  required
-           TZ="EET-2EEST,M3.5.0/3,M10.5.0/4"  if POSIX conformance is required
+       and older timestamps need not be handled accurately.
-           and older timestamps need not be handled accurately.
 
-           The localtime(3) function normally uses the first ttinfo  structure
+       The  localtime(3)  function normally uses the first ttinfo structure in
-           in  the  file if either tzh_timecnt is zero or the time argument is
+       the file if either tzh_timecnt is zero or the  time  argument  is  less
-           less than the first transition time recorded in the file.
+       than the first transition time recorded in the file.
 
    Version 2 format
-       For version-2-format timezone files, the  above  header  and  data  are
+       For  version-2-format  timezone  files,  the  above header and data are
-       followed  by  a second header and data, identical in format except that
+       followed by a second header and data, identical in format  except  that
-       eight bytes are used for each transition  time  or  leap  second  time.
+       eight  bytes  are  used  for  each transition time or leap second time.
-       (Leap  second  counts  remain four bytes.)  After the second header and
+       (Leap second counts remain four bytes.)  After the  second  header  and
-       data comes a newline-enclosed string in the style of the contents of  a
+       data  comes a newline-enclosed string in the style of the contents of a
-       POSIX.1-2017  TZ  environment  variable,  for  use in handling instants
+       proleptic TZ, for use in handling instants after  the  last  transition
-       after the last transition time stored in the file or for  all  instants
+       time  stored  in  the  file  or  for  all  instants  if the file has no
-       if  the file has no transitions.  The TZ string is empty (i.e., nothing
+       transitions.  The  TZ  string  is  empty  (i.e.,  nothing  between  the
-       between the newlines) if there is no POSIX.1-2017-style  representation
+       newlines)  if  there  is no proleptic representation for such instants.
-       for  such  instants.   If  nonempty,  the TZ string must agree with the
+       If nonempty, the TZ string must agree with the local  time  type  after
-       local time type after the last transition time if present in the eight-
+       the  last  transition  time  if  present  in  the  eight-byte data; for
-       byte data; for example, given  the  string  "WET0WEST,M3.5.0/1,M10.5.0"
+       example, given the string "WET0WEST,M3.5.0/1,M10.5.0" then  if  a  last
-       then  if a last transition time is in July, the transition's local time
+       transition  time  is  in  July,  the  transition's local time type must
-       type must specify a daylight-saving time abbreviated "WEST" that is one
+       specify a daylight-saving time abbreviated "WEST" that is one hour east
-       hour east of UT.  Also, if there is at least one transition, time  type
+       of UT.  Also, if there is at least  one  transition,  time  type  0  is
-       0 is associated with the time period from the indefinite past up to but
+       associated  with the time period from the indefinite past up to but not
-       not including the earliest transition time.
+       including the earliest transition time.
 
    Version 3 format
-       For  version-3-format  timezone  files, the TZ string may use two minor
+       For version-3-format timezone files, a TZ string (see newtzset(3))  may
-       extensions to the POSIX.1-2017 TZ format, as described in  newtzset(3).
+       use the following POSIX.1-2024 extensions to POSIX.1-2017: First, as in
-       First,  the  hours part of its transition times may be signed and range
+       TZ="<-02>2<-01>,M3.5.0/-1,M10.5.0/0",  the hours part of its transition
-       from -167 through 167 instead of  the  POSIX-required  unsigned  values
+       times may be signed and range from -167 through 167  instead  of  being
-       from  0  through  24.   Second,  DST is in effect all year if it starts
+       limited   to  unsigned  values  from  0  through  24.   Second,  as  in
-       January 1 at 00:00 and ends December 31 at 24:00  plus  the  difference
+       TZ="XXX3EDT4,0/0,J365/23", DST is in  effect  all  year  if  it  starts
+       January  1  at  00:00 and ends December 31 at 24:00 plus the difference
        between daylight saving and standard time.
 
    Version 4 format
-       For  version-4-format TZif files, the first leap second record can have
+       For version-4-format TZif files, the first leap second record can  have
-       a correction that is neither +1 nor -1, to represent truncation of  the
+       a  correction that is neither +1 nor -1, to represent truncation of the
-       TZif  file  at the start.  Also, if two or more leap second transitions
+       TZif file at the start.  Also, if two or more leap  second  transitions
-       are present and the last entry's correction equals  the  previous  one,
+       are  present  and  the last entry's correction equals the previous one,
-       the  last entry denotes the expiration of the leap second table instead
+       the last entry denotes the expiration of the leap second table  instead
-       of a leap second; timestamps after this expiration  are  unreliable  in
+       of  a  leap  second; timestamps after this expiration are unreliable in
-       that  future  releases  will  likely  add leap second entries after the
+       that future releases will likely add  leap  second  entries  after  the
-       expiration, and the added leap seconds will change how  post-expiration
+       expiration,  and the added leap seconds will change how post-expiration
        timestamps are treated.
 
    Interoperability considerations
        Future changes to the format may append more data.
 
-       Version  1  files  are  considered  a  legacy  format and should not be
+       Version 1 files are considered  a  legacy  format  and  should  not  be
        generated, as they do not support transition times after the year 2038.
-       Readers that understand only  Version  1  must  ignore  any  data  that
+       Readers  that  understand  only  Version  1  must  ignore any data that
        extends beyond the calculated end of the version 1 data block.
 
        Other than version 1, writers should generate the lowest version number
-       needed  by  a  file's  data.   For  example, a writer should generate a
+       needed by a file's data.  For  example,  a  writer  should  generate  a
-       version 4 file only if its leap  second  table  either  expires  or  is
+       version  4  file  only  if  its  leap second table either expires or is
-       truncated  at the start.  Likewise, a writer not generating a version 4
+       truncated at the start.  Likewise, a writer not generating a version  4
-       file should generate a version 3 file only if TZ string extensions  are
+       file  should generate a version 3 file only if TZ string extensions are
        necessary to accurately model transition times.
 
-       The  sequence  of time changes defined by the version 1 header and data
+       The sequence of time changes defined by the version 1 header  and  data
-       block should be a contiguous sub-sequence of the time  changes  defined
+       block  should  be a contiguous sub-sequence of the time changes defined
-       by  the  version  2+  header  and  data block, and by the footer.  This
+       by the version 2+ header and data  block,  and  by  the  footer.   This
-       guideline helps  obsolescent  version  1  readers  agree  with  current
+       guideline  helps  obsolescent  version  1  readers  agree  with current
-       readers  about  timestamps within the contiguous sub-sequence.  It also
+       readers about timestamps within the contiguous sub-sequence.   It  also
-       lets writers not supporting obsolescent readers use  a  tzh_timecnt  of
+       lets  writers  not  supporting obsolescent readers use a tzh_timecnt of
        zero in the version 1 data block to save space.
 
-       When  a  TZif  file  contains a leap second table expiration time, TZif
+       When a TZif file contains a leap second  table  expiration  time,  TZif
-       readers should either refuse to process post-expiration timestamps,  or
+       readers  should either refuse to process post-expiration timestamps, or
-       process  them as if the expiration time did not exist (possibly with an
+       process them as if the expiration time did not exist (possibly with  an
        error indication).
 
        Time zone designations should consist of at least three (3) and no more
-       than six (6) ASCII characters from the set of alphanumerics,  "-",  and
+       than  six  (6) ASCII characters from the set of alphanumerics, "-", and
-       "+".   This  is for compatibility with POSIX requirements for time zone
+       "+".  This is for compatibility with POSIX requirements for  time  zone
        abbreviations.
 
-       When reading a version 2 or higher  file,  readers  should  ignore  the
+       When  reading  a  version  2  or higher file, readers should ignore the
        version 1 header and data block except for the purpose of skipping over
        them.
 
-       Readers  should  calculate  the  total  lengths of the headers and data
+       Readers should calculate the total lengths  of  the  headers  and  data
        blocks and check that they all fit within the actual file size, as part
        of a validity check for the file.
 
-       When a positive leap second occurs,  readers  should  append  an  extra
+       When  a  positive  leap  second  occurs, readers should append an extra
-       second  to  the local minute containing the second just before the leap
+       second to the local minute containing the second just before  the  leap
-       second.  If this occurs when the UTC offset is not  a  multiple  of  60
+       second.   If  this  occurs  when the UTC offset is not a multiple of 60
-       seconds,  the  leap  second  occurs earlier than the last second of the
+       seconds, the leap second occurs earlier than the  last  second  of  the
-       local minute and the minute's  remaining  local  seconds  are  numbered
+       local  minute  and  the  minute's  remaining local seconds are numbered
        through 60 instead of the usual 59; the UTC offset is unaffected.
 
    Common interoperability issues
-       This  section  documents  common  problems  in  reading or writing TZif
+       This section documents common  problems  in  reading  or  writing  TZif
-       files.  Most of these are problems in generating TZif files for use  by
+       files.   Most of these are problems in generating TZif files for use by
        older readers.  The goals of this section are:
 
-         o  to  help  TZif  writers output files that avoid common pitfalls in
+         o  to help TZif writers output files that avoid  common  pitfalls  in
             older or buggy TZif readers,
 
-         o  to help TZif readers avoid  common  pitfalls  when  reading  files
+         o  to  help  TZif  readers  avoid  common pitfalls when reading files
             generated by future TZif writers, and
 
          o  to help any future specification authors see what sort of problems
             arise when the TZif format is changed.
 
-       When  new  versions of the TZif format have been defined, a design goal
+       When new versions of the TZif format have been defined, a  design  goal
-       has been that a reader can successfully use a TZif  file  even  if  the
+       has  been  that  a  reader can successfully use a TZif file even if the
-       file  is of a later TZif version than what the reader was designed for.
+       file is of a later TZif version than what the reader was designed  for.
-       When complete compatibility was not achieved, an attempt  was  made  to
+       When  complete  compatibility  was not achieved, an attempt was made to
-       limit  glitches  to  rarely  used  timestamps  and allow simple partial
+       limit glitches to rarely  used  timestamps  and  allow  simple  partial
-       workarounds in writers designed to  generate  new-version  data  useful
+       workarounds  in  writers  designed  to generate new-version data useful
-       even  for  older-version  readers.   This  section attempts to document
+       even for older-version readers.   This  section  attempts  to  document
-       these compatibility issues and workarounds,  as  well  as  to  document
+       these  compatibility  issues  and  workarounds,  as well as to document
        other common bugs in readers.
 
        Interoperability problems with TZif include the following:
 
-         o  Some   readers   examine  only  version  1  data.   As  a  partial
+         o  Some  readers  examine  only  version  1  data.   As   a   partial
-            workaround, a  writer  can  output  as  much  version  1  data  as
+            workaround,  a  writer  can  output  as  much  version  1  data as
-            possible.   However,  a  reader  should ignore version 1 data, and
+            possible.  However, a reader should ignore  version  1  data,  and
-            should use version 2+ data even if the reader's native  timestamps
+            should  use version 2+ data even if the reader's native timestamps
             have only 32 bits.
 
-         o  Some  readers  designed  for  version 2 might mishandle timestamps
+         o  Some readers designed for version  2  might  mishandle  timestamps
-            after a version 3 or higher file's last transition,  because  they
+            after  a  version 3 or higher file's last transition, because they
-            cannot parse extensions to POSIX.1-2017 in the TZ-like string.  As
+            cannot parse the POSIX.1-2024 extensions to  POSIX.1-2017  in  the
-            a  partial  workaround,  a writer can output more transitions than
+            proleptic TZ string.  As a partial workaround, a writer can output
-            necessary, so that only far-future timestamps  are  mishandled  by
+            more   transitions   than   necessary,  so  that  only  far-future
-            version 2 readers.
+            timestamps are mishandled by version 2 readers.
 
-         o  Some  readers  designed  for  version  2  do not support permanent
+         o  Some readers designed for  version  2  do  not  support  permanent
-            daylight saving time with transitions after 24:00  -  e.g.,  a  TZ
+            daylight  saving  time  with  transitions after 24:00 - e.g., a TZ
-            string  "EST5EDT,0/0,J365/25"  denoting permanent Eastern Daylight
+            string "EST5EDT,0/0,J365/25" denoting permanent  Eastern  Daylight
-            Time (-04).  As a workaround, a  writer  can  substitute  standard
+            Time  (-04).   As  a  workaround, a writer can substitute standard
-            time  for  two time zones east, e.g., "XXX3EDT4,0/0,J365/23" for a
+            time for two time zones east, e.g., "XXX3EDT4,0/0,J365/23"  for  a
-            time zone with a never-used standard time (XXX, -03) and  negative
+            time  zone with a never-used standard time (XXX, -03) and negative
-            daylight  saving  time  (EDT,  -04) all year.  Alternatively, as a
+            daylight saving time (EDT, -04) all  year.   Alternatively,  as  a
-            partial workaround a writer can substitute standard time  for  the
+            partial  workaround  a writer can substitute standard time for the
             next time zone east - e.g., "AST4" for permanent Atlantic Standard
             Time (-04).
 
-         o  Some  readers designed for version 2 or 3, and that require strict
+         o  Some readers designed for version 2 or 3, and that require  strict
-            conformance to RFC 8536, reject version 4 files whose leap  second
+            conformance  to RFC 8536, reject version 4 files whose leap second
             tables are truncated at the start or that end in expiration times.
 
          o  Some  readers  ignore  the  footer,  and  instead  predict  future
-            timestamps from the time  type  of  the  last  transition.   As  a
+            timestamps  from  the  time  type  of  the  last transition.  As a
-            partial  workaround,  a  writer  can  output more transitions than
+            partial workaround, a writer  can  output  more  transitions  than
             necessary.
 
+         o  Some  stripped-down  readers ignore everything but the footer, and
+            use its proleptic TZ string to calculate all timestamps.  Although
+            this approach often works for current and  future  timestamps,  it
+            obviously  has problems with past timestamps, and even for current
+            timestamps it can fail for settings  like  TZ="Africa/Casablanca".
+            This  corresponds  to  a TZif file containing explicit transitions
+            through the year 2087, followed by  a  footer  containing  the  TZ
+            string  "<+01>-1",  which should be used only for timestamps after
+            the last explicit transition.
+
          o  Some readers do not use time type  0  for  timestamps  before  the
             first transition, in that they infer a time type using a heuristic
             that does not always select time type 0.  As a partial workaround,

tzfile.h

@@ -76,14 +76,16 @@ struct tzhead {
 ** If tzh_version is '2' or greater, the above is followed by a second instance
 ** of tzhead and a second instance of the data in which each coded transition
 ** time uses 8 rather than 4 chars,
-** then a POSIX-TZ-environment-variable-style string for use in handling
+** then a POSIX.1-2017 proleptic TZ string for use in handling
 ** instants after the last transition time stored in the file
 ** (with nothing between the newlines if there is no POSIX.1-2017
 ** representation for such instants).
 **
-** If tz_version is '3' or greater, the above is extended as follows.
+** If tz_version is '3' or greater, the TZ string can be any POSIX.1-2024
+** proleptic TZ string, which means the above is extended as follows.
 ** First, the TZ string's hour offset may range from -167
-** through 167 as compared to the POSIX-required 0 through 24.
+** through 167 as compared to the range 0 through 24 required
+** by POSIX.1-2017 and earlier.
 ** Second, its DST start time may be January 1 at 00:00 and its stop
 ** time December 31 at 24:00 plus the difference between DST and
 ** standard time, indicating DST all year.

tzselect.ksh

@@ -20,12 +20,6 @@ REPORT_BUGS_TO=tz@iana.org
 #	Korn Shell <http://www.kornshell.com/>
 #	MirBSD Korn Shell <http://www.mirbsd.org/mksh.htm>
 #
-# For portability to Solaris 10 /bin/sh (supported by Oracle through
-# January 2027) this script avoids some POSIX features and common
-# extensions, such as $(...), $((...)), ! CMD, unquoted ^, ${#ID},
-# ${ID##PAT}, ${ID%%PAT}, and $10.  Although some of these constructs
-# work sometimes, it's simpler to avoid them entirely.
-#
 # This script also uses several features of POSIX awk.
 # If your host lacks awk, or has an old awk that does not conform to POSIX,
 # you can use any of the following free programs instead:
@@ -45,7 +39,6 @@ set -f
 
 # Specify default values for environment variables if they are unset.
 : ${AWK=awk}
-: ${PWD=`pwd`}
 : ${TZDIR=$PWD}
 
 # Output one argument as-is to standard output, with trailing newline.
@@ -54,13 +47,6 @@ say() {
   printf '%s\n' "$1"
 }
 
-# Check for awk POSIX compliance.
-($AWK -v x=y 'BEGIN { exit 123 }') <>/dev/null >&0 2>&0
-[ $? = 123 ] || {
-  say >&2 "$0: Sorry, your '$AWK' program is not POSIX compatible."
-  exit 1
-}
-
 coord=
 location_limit=10
 zonetabtype=zone1970
@@ -117,8 +103,7 @@ then
 else
   doselect() {
     # Field width of the prompt numbers.
-    print_nargs_length="BEGIN {print length(\"$#\");}"
+    select_width=${##}
-    select_width=`$AWK "$print_nargs_length"`
 
     select_i=
 
@@ -129,14 +114,14 @@ else
 	select_i=0
 	for select_word
 	do
-	  select_i=`$AWK "BEGIN { print $select_i + 1 }"`
+	  select_i=$(($select_i + 1))
 	  printf >&2 "%${select_width}d) %s\\n" $select_i "$select_word"
 	done;;
       *[!0-9]*)
 	echo >&2 'Please enter a number in range.';;
       *)
 	if test 1 -le $select_i && test $select_i -le $#; then
-	  shift `$AWK "BEGIN { print $select_i - 1 }"`
+	  shift $(($select_i - 1))
 	  select_result=$1
 	  break
 	fi
@@ -170,7 +155,7 @@ do
   esac
 done
 
-shift `$AWK "BEGIN { print $OPTIND - 1 }"`
+shift $(($OPTIND - 1))
 case $# in
 0) ;;
 *) say >&2 "$0: $1: unknown argument"; exit 1
@@ -178,11 +163,13 @@ esac
 
 # translit=true to try transliteration.
 # This is false if U+12345 CUNEIFORM SIGN URU TIMES KI has length 1
-# which means awk (and presumably the shell) do not need transliteration.
+# which means the shell and (presumably) awk do not need transliteration.
-if $AWK 'BEGIN { u12345 = "\360\222\215\205"; exit length(u12345) == 1 }'; then
+# It is true if the byte string has some other length in characters, or
-  translit=true
+# if this is a POSIX.1-2017 or earlier shell that does not support $'...'.
-else
+CUNEIFORM_SIGN_URU_TIMES_KI=$'\360\222\215\205'
-  translit=false
+if test ${#CUNEIFORM_SIGN_URU_TIMES_KI} = 1
+then translit=false
+else translit=true
 fi
 
 # Read into shell variable $1 the contents of file $2.
@@ -192,10 +179,10 @@ fi
 # if that does not work, fall back on 'cat'.
 read_file() {
   { $translit && {
-    eval "$1=\`(iconv -f UTF-8 -t //TRANSLIT) 2>/dev/null <\"\$2\"\`" ||
+    eval "$1=\$( (iconv -f UTF-8 -t //TRANSLIT) 2>/dev/null <\"\$2\")" ||
-    eval "$1=\`(iconv -f UTF-8) 2>/dev/null <\"\$2\"\`"
+    eval "$1=\$( (iconv -f UTF-8) 2>/dev/null <\"\$2\")"
   }; } ||
-  eval "$1=\`cat <\"\$2\"\`" || {
+  eval "$1=\$(cat <\"\$2\")" || {
     say >&2 "$0: time zone files are not set up correctly"
     exit 1
   }
@@ -403,7 +390,7 @@ while
     echo >&2 \
       'Please select a continent, ocean, "coord", "TZ", "time", or "now".'
 
-    quoted_continents=`
+    quoted_continents=$(
       $AWK '
 	function handle_entry(entry) {
 	  entry = substr(entry, 1, index(entry, "/") - 1)
@@ -433,12 +420,12 @@ while
       sort -u |
       tr '\n' ' '
       echo ''
-    `
+    )
 
     eval '
       doselect '"$quoted_continents"' \
 	"coord - I want to use geographical coordinates." \
-	"TZ - I want to specify the timezone using a POSIX.1-2017 TZ string." \
+	"TZ - I want to specify the timezone using a proleptic TZ string." \
 	"time - I know local time already." \
 	"now - Like \"time\", but configure only for timestamps from now on."
       continent=$select_result
@@ -462,16 +449,17 @@ while
 
   case $continent in
   TZ)
-    # Ask the user for a POSIX.1-2017 TZ string.  Check that it conforms.
+    # Ask the user for a proleptic TZ string.  Check that it conforms.
     check_POSIX_TZ_string='
       BEGIN {
 	tz = substr(ARGV[1], 2)
 	ARGV[1] = ""
 	tzname = ("(<[[:alnum:]+-][[:alnum:]+-][[:alnum:]+-]+>" \
 		  "|[[:alpha:]][[:alpha:]][[:alpha:]]+)")
-	time = ("(2[0-4]|[0-1]?[0-9])" \
+	sign = "[-+]?"
-		"(:[0-5][0-9](:[0-5][0-9])?)?")
+	hhmm = "(:[0-5][0-9](:[0-5][0-9])?)?"
-	offset = "[-+]?" time
+	offset = sign "(2[0-4]|[0-1]?[0-9])" hhmm
+	time = sign "(16[0-7]|(1[0-5]|[0-9]?)[0-9])" hhmm
 	mdate = "M([1-9]|1[0-2])\\.[1-5]\\.[0-6]"
 	jdate = ("((J[1-9]|[0-9]|J?[1-9][0-9]" \
 		 "|J?[1-2][0-9][0-9])|J?3[0-5][0-9]|J?36[0-5])")
@@ -492,7 +480,7 @@ while
       read tz
       $AWK "$check_POSIX_TZ_string" ="$tz"
     do
-      say >&2 "'$tz' is not a conforming POSIX.1-2017 timezone string."
+      say >&2 "'$tz' is not a conforming POSIX proleptic TZ string."
     done
     TZ_for_date=$tz;;
   *)
@@ -507,14 +495,14 @@ while
 	  '74 degrees 3 minutes west.'
 	read coord
       esac
-      distance_table=`
+      distance_table=$(
 	$AWK \
 	  "$output_distances_or_times" \
 	  ="$coord" ="$TZ_COUNTRY_TABLE" ="$TZ_ZONE_TABLE" |
 	sort -n |
 	$AWK "{print} NR == $location_limit { exit }"
-      `
+      )
-      regions=`
+      regions=$(
 	$AWK '
 	  BEGIN {
 	    distance_table = substr(ARGV[1], 2)
@@ -526,13 +514,13 @@ while
 	    }
 	  }
 	' ="$distance_table"
-      `
+      )
       echo >&2 'Please select one of the following timezones,'
       echo >&2 'listed roughly in increasing order' \
 	"of distance from $coord".
       doselect $regions
       region=$select_result
-      tz=`
+      tz=$(
 	$AWK '
 	  BEGIN {
 	    distance_table = substr(ARGV[1], 2)
@@ -546,22 +534,22 @@ while
 	    }
 	  }
 	' ="$distance_table" ="$region"
-      `;;
+      );;
     *)
       case $continent in
       now|time)
 	minute_format='%a %b %d %H:%M'
-	old_minute=`TZ=UTC0 date +"$minute_format"`
+	old_minute=$(TZ=UTC0 date +"$minute_format")
 	for i in 1 2 3
 	do
-	  time_table_command=`
+	  time_table_command=$(
 	    $AWK \
 	      -v output_times=1 \
 	      "$output_distances_or_times" \
 	      = = ="$TZ_ZONE_TABLE"
-	  `
+	  )
-	  time_table=`eval "$time_table_command"`
+	  time_table=$(eval "$time_table_command")
-	  new_minute=`TZ=UTC0 date +"$minute_format"`
+	  new_minute=$(TZ=UTC0 date +"$minute_format")
 	  case $old_minute in
 	  "$new_minute") break
 	  esac
@@ -569,11 +557,11 @@ while
 	done
 	echo >&2 "The system says Universal Time is $new_minute."
 	echo >&2 "Assuming that's correct, what is the local time?"
-	sorted_table=`say "$time_table" | sort -k2n -k2,5 -k1n` || {
+	sorted_table=$(say "$time_table" | sort -k2n -k2,5 -k1n) || {
 	  say >&2 "$0: cannot sort time table"
 	  exit 1
 	}
-	eval doselect `
+	eval doselect $(
 	  $AWK '
 	    BEGIN {
 	      sorted_table = substr(ARGV[1], 2)
@@ -590,10 +578,10 @@ while
 	      }
 	    }
 	  ' ="$sorted_table"
-	`
+	)
 	time=$select_result
 	continent_re='^'
-	zone_table=`
+	zone_table=$(
 	  $AWK '
 	    BEGIN {
 	      time = substr(ARGV[1], 2)
@@ -609,13 +597,13 @@ while
 	      }
 	    }
 	  ' ="$time" ="$time_table"
-	`
+	)
-	countries=`
+	countries=$(
 	  $AWK \
 	    "$output_country_list" \
 	    ="$continent_re" ="$TZ_COUNTRY_TABLE" ="$zone_table" |
 	  sort -f
-	`
+	)
 	;;
       *)
 	continent_re="^$continent/"
@@ -623,16 +611,16 @@ while
       esac
 
       # Get list of names of countries in the continent or ocean.
-      countries=`
+      countries=$(
 	$AWK \
 	  "$output_country_list" \
 	  ="$continent_re" ="$TZ_COUNTRY_TABLE" ="$zone_table" |
 	sort -f
-      `
+      )
       # If all zone table entries have comments, and there are
       # at most 22 entries, asked based on those comments.
       # This fits the prompt onto old-fashioned 24-line screens.
-      regions=`
+      regions=$(
 	$AWK '
 	  BEGIN {
 	    TZ_ZONE_TABLE = substr(ARGV[1], 2)
@@ -653,7 +641,7 @@ while
 		print comment[i]
 	  }
 	' ="$zone_table"
-      `
+      )
 
       # If there's more than one country, ask the user which one.
       case $countries in
@@ -669,7 +657,7 @@ while
 
 
       # Get list of timezones in the country.
-      regions=`
+      regions=$(
 	$AWK '
 	  BEGIN {
 	    country = substr(ARGV[1], 2)
@@ -696,7 +684,7 @@ while
 	    }
 	  }
 	' ="$country" ="$TZ_COUNTRY_TABLE" ="$zone_table"
-      `
+      )
 
       # If there's more than one region, ask the user which one.
       case $regions in
@@ -707,7 +695,7 @@ while
       esac
 
       # Determine tz from country and region.
-      tz=`
+      tz=$(
 	$AWK '
 	  BEGIN {
 	    country = substr(ARGV[1], 2)
@@ -735,7 +723,7 @@ while
 	    }
 	  }
 	' ="$country" ="$region" ="$TZ_COUNTRY_TABLE" ="$zone_table"
-      `
+      )
     esac
 
     # Make sure the corresponding zoneinfo file exists.
@@ -754,14 +742,11 @@ while
   extra_info=
   for i in 1 2 3 4 5 6 7 8
   do
-    TZdate=`LANG=C TZ="$TZ_for_date" date`
+    TZdate=$(LANG=C TZ="$TZ_for_date" date)
-    UTdate=`LANG=C TZ=UTC0 date`
+    UTdate=$(LANG=C TZ=UTC0 date)
-    if $AWK '
+    TZsecsetc=${TZdate##*[0-5][0-9]:}
-	  function getsecs(d) {
+    UTsecsetc=${UTdate##*[0-5][0-9]:}
-	    return match(d, /.*:[0-5][0-9]/) ? substr(d, RLENGTH - 1, 2) : ""
+    if test "${TZsecsetc%%[!0-9]*}" = "${UTsecsetc%%[!0-9]*}"
-	  }
-	  BEGIN { exit getsecs(ARGV[1]) != getsecs(ARGV[2]) }
-       ' ="$TZdate" ="$UTdate"
     then
       extra_info="
 Selected time is now:	$TZdate.
@@ -801,7 +786,7 @@ done
 
 case $SHELL in
 *csh) file=.login line="setenv TZ '$tz'";;
-*)    file=.profile line="TZ='$tz'; export TZ"
+*)    file=.profile line="export TZ='$tz'"
 esac
 
 test -t 1 && say >&2 "

version

@@ -1 +1 @@
-2024a
+2024b

workman.sh

@@ -7,8 +7,7 @@
 if (type nroff && type perl) >/dev/null 2>&1; then
 
   # Tell groff not to emit SGR escape sequences (ANSI color escapes).
-  GROFF_NO_SGR=1
+  export GROFF_NO_SGR=1
-  export GROFF_NO_SGR
 
   echo ".am TH
 .hy 0

zdump.8

@@ -152,7 +152,8 @@ tabbed columns line up.)
 .nf
 .sp
 .if \n(.g .ft CR
-.in +2
+.if t .in +.5i
+.if n .in +2
 .nr w \w'1896-01-13  'u+\n(.i
 .ta \w'1896-01-13\0\0'u +\w'12:01:26\0\0'u +\w'-103126\0\0'u +\w'HWT\0\0'u
 TZ="Pacific/Honolulu"

zdump.c

@@ -89,7 +89,7 @@ static bool	warned;
 static bool	errout;
 
 static char const *abbr(struct tm const *);
-ATTRIBUTE_REPRODUCIBLE static intmax_t delta(struct tm *, struct tm *);
+static intmax_t delta(struct tm *, struct tm *);
 static void dumptime(struct tm const *);
 static time_t hunt(timezone_t, time_t, time_t, bool);
 static void show(timezone_t, char *, time_t, bool);
@@ -97,7 +97,7 @@ static void showextrema(timezone_t, char *, time_t, struct tm *, time_t);
 static void showtrans(char const *, struct tm const *, time_t, char const *,
 		      char const *);
 static const char *tformat(void);
-ATTRIBUTE_REPRODUCIBLE static time_t yeartot(intmax_t);
+ATTRIBUTE_PURE_114833 static time_t yeartot(intmax_t);
 
 /* Is C an ASCII digit?  */
 static bool
@@ -134,7 +134,7 @@ size_overflow(void)
 
 /* Return A + B, exiting if the result would overflow either ptrdiff_t
    or size_t.  A and B are both nonnegative.  */
-ATTRIBUTE_REPRODUCIBLE static ptrdiff_t
+ATTRIBUTE_PURE_114833 static ptrdiff_t
 sumsize(ptrdiff_t a, ptrdiff_t b)
 {
 #ifdef ckd_add
@@ -162,7 +162,7 @@ xstrsize(char const *str)
 
 /* Return a pointer to a newly allocated buffer of size SIZE, exiting
    on failure.  SIZE should be positive.  */
-ATTRIBUTE_MALLOC static void *
+static void *
 xmalloc(ptrdiff_t size)
 {
   void *p = malloc(size);
@@ -932,7 +932,7 @@ showextrema(timezone_t tz, char *zone, time_t lo, struct tm *lotmp, time_t hi)
 # include <stdarg.h>
 
 /* A substitute for snprintf that is good enough for zdump.  */
-ATTRIBUTE_FORMAT((printf, 3, 4)) static int
+static int
 my_snprintf(char *s, size_t size, char const *format, ...)
 {
   int n;

zic.8

@@ -171,7 +171,7 @@ boundaries, particularly if
 causes a TZif file to contain explicit entries for
 .RI pre- hi
 transitions rather than concisely representing them
-with an extended POSIX.1-2017 TZ string.
+with a proleptic TZ string.
 Also see the
 .B "\*-b slim"
 option for another way to shrink output size.
@@ -181,10 +181,10 @@ Generate redundant trailing explicit transitions for timestamps
 that occur less than
 .I hi
 seconds since the Epoch, even though the transitions could be
-more concisely represented via the extended POSIX.1-2017 TZ string.
+more concisely represented via the proleptic TZ string.
 This option does not affect the represented timestamps.
 Although it accommodates nonstandard TZif readers
-that ignore the extended POSIX.1-2017 TZ string,
+that ignore the proleptic TZ string,
 it increases the size of the altered output files.
 .TP
 .BI "\*-t " file
@@ -245,10 +245,10 @@ for
 .PP
 The output file does not contain all the information about the
 long-term future of a timezone, because the future cannot be summarized as
-an extended POSIX.1-2017 TZ string.  For example, as of 2023 this problem
+a proleptic TZ string.  For example, as of 2023 this problem
 occurs for Morocco's daylight-saving rules, as these rules are based
 on predictions for when Ramadan will be observed, something that
-an extended POSIX.1-2017 TZ string cannot represent.
+a proleptic TZ string cannot represent.
 .PP
 The output contains data that may not be handled properly by client
 code designed for older
@@ -558,12 +558,14 @@ begin the field with a minus sign if time must be subtracted from UT.
 .TP
 .B RULES
 The name of the rules that apply in the timezone or,
-alternatively, a field in the same format as a rule-line SAVE column,
+alternatively, a field in the same format as a rule-line
+.B SAVE
+field,
 giving the amount of time to be added to local standard time
 and whether the resulting time is standard or daylight saving.
-If this field is
+Standard time applies if this field is
 .B \*-
-then standard time always applies.
+or for timestamps occurring before any rule takes effect.
 When an amount of time is given, only the sum of standard time and
 this amount matters.
 .TP
@@ -571,9 +573,13 @@ this amount matters.
 The format for time zone abbreviations.
 The pair of characters
 .B %s
-is used to show where the
+shows where to put the time zone abbreviation's variable part,
-.q "variable part"
+which is taken from the
-of the time zone abbreviation goes.
+.B LETTER/S
+field of the corresponding rule;
+any timestamps that precede the earliest rule use the
+.B LETTER/S
+of the earliest standard-time rule (which in this case must exist).
 Alternatively, a format can use the pair of characters
 .B %z
 to stand for the UT offset in the form
@@ -663,7 +669,7 @@ Rule	US	1967	1973	-	Apr	lastSun	2:00	1:00	D
 .ta \w'# Zone\0\0'u +\w'America/Menominee\0\0'u +\w'STDOFF\0\0'u +\w'RULES\0\0'u +\w'FORMAT\0\0'u
 # Zone	NAME	STDOFF	RULES	FORMAT	[UNTIL]
 Zone	America/Menominee	\*-5:00	\*-	EST	1973 Apr 29 2:00
-	\*-6:00	US	C%sT
+		\*-6:00	US	C%sT
 .sp
 .in
 .fi
@@ -767,16 +773,16 @@ or
 if the leap second time given by the other fields should be interpreted as
 local (wall clock) time.
 .PP
-Rolling leap seconds were implemented back when it was not
+Rolling leap seconds would let one see
-clear whether common practice was rolling or stationary,
-with concerns that one would see
 Times Square ball drops where there'd be a
 .q "3... 2... 1... leap... Happy New Year"
 countdown, placing the leap second at
 midnight New York time rather than midnight UTC.
-However, this countdown style does not seem to have caught on,
+Although stationary leap seconds are the common practice,
-which means rolling leap seconds are not used in practice;
+rolling leap seconds can be useful in specialized applications
-also, they are not supported if the
+like SMPTE timecodes that may prefer to put leap second
+discontinuities at the end of a local broadcast day.
+However, rolling leap seconds are not supported if the
 .B \*-r
 option is used.
 .PP

zic.8.txt

@@ -77,16 +77,16 @@ OPTIONS
               due  to  the  need  to represent the timestamp range boundaries,
               particularly if hi  causes  a  TZif  file  to  contain  explicit
               entries   for   pre-hi   transitions   rather   than   concisely
-              representing them with an extended POSIX.1-2017 TZ string.  Also
+              representing them with a proleptic TZ string.  Also see  the  -b
-              see the -b slim option for another way to shrink output size.
+              slim option for another way to shrink output size.
 
-       -R @hi Generate redundant trailing explicit transitions for  timestamps
+       -R @hi Generate  redundant trailing explicit transitions for timestamps
               that occur less than hi seconds since the Epoch, even though the
-              transitions could be more concisely represented via the extended
+              transitions  could  be  more  concisely  represented   via   the
-              POSIX.1-2017  TZ  string.   This  option  does  not  affect  the
+              proleptic   TZ   string.    This  option  does  not  affect  the
               represented timestamps.  Although  it  accommodates  nonstandard
-              TZif readers that ignore the extended POSIX.1-2017 TZ string, it
+              TZif  readers  that ignore the proleptic TZ string, it increases
-              increases the size of the altered output files.
+              the size of the altered output files.
 
        -t file
               When creating local time information, put the configuration link
@@ -97,34 +97,33 @@ OPTIONS
               The input specifies a link to a link, something not supported by
               some older parsers, including zic itself through release 2022e.
 
-              A  year  that  appears  in  a  data file is outside the range of
+              A year that appears in a data  file  is  outside  the  range  of
               representable years.
 
               A time of 24:00 or more appears in the input.  Pre-1998 versions
-              of zic prohibit 24:00,  and  pre-2007  versions  prohibit  times
+              of  zic  prohibit  24:00,  and  pre-2007 versions prohibit times
               greater than 24:00.
 
-              A  rule  goes  past  the  start  or  end of the month.  Pre-2004
+              A rule goes past the  start  or  end  of  the  month.   Pre-2004
               versions of zic prohibit this.
 
               A time zone abbreviation uses a %z format.  Pre-2015 versions of
               zic do not support this.
 
-              A timestamp contains fractional seconds.  Pre-2018  versions  of
+              A  timestamp  contains fractional seconds.  Pre-2018 versions of
               zic do not support this.
 
               The input contains abbreviations that are mishandled by pre-2018
-              versions  of  zic  due  to  a  longstanding  coding  bug.  These
+              versions of  zic  due  to  a  longstanding  coding  bug.   These
-              abbreviations include "L" for "Link", "mi" for "min",  "Sa"  for
+              abbreviations  include  "L" for "Link", "mi" for "min", "Sa" for
               "Sat", and "Su" for "Sun".
 
-              The  output  file does not contain all the information about the
+              The output file does not contain all the information  about  the
-              long-term future of a timezone, because  the  future  cannot  be
+              long-term  future  of  a  timezone, because the future cannot be
-              summarized  as an extended POSIX.1-2017 TZ string.  For example,
+              summarized as a proleptic TZ string.  For example,  as  of  2023
-              as of 2023 this problem  occurs  for  Morocco's  daylight-saving
+              this  problem  occurs  for  Morocco's  daylight-saving rules, as
-              rules,  as these rules are based on predictions for when Ramadan
+              these rules are based on predictions for when  Ramadan  will  be
-              will be observed, something that  an  extended  POSIX.1-2017  TZ
+              observed, something that a proleptic TZ string cannot represent.
-              string cannot represent.
 
               The  output  contains  data  that may not be handled properly by
               client code  designed  for  older  zic  output  formats.   These
@@ -309,24 +308,28 @@ FILES
 
        RULES  The  name  of  the  rules  that  apply  in  the   timezone   or,
               alternatively,  a  field  in the same format as a rule-line SAVE
-              column, giving the amount of time to be added to local  standard
+              field, giving the amount of time to be added to  local  standard
               time  and  whether  the  resulting  time is standard or daylight
-              saving.  If this field is - then standard time  always  applies.
+              saving.  Standard time  applies  if  this  field  is  -  or  for
-              When  an  amount of time is given, only the sum of standard time
+              timestamps  occurring  before  any  rule  takes effect.  When an
-              and this amount matters.
+              amount of time is given, only the sum of standard time and  this
+              amount matters.
 
-       FORMAT The format for time zone abbreviations.  The pair of  characters
+       FORMAT The  format for time zone abbreviations.  The pair of characters
-              %s  is  used  to show where the "variable part" of the time zone
+              %s shows where to put  the  time  zone  abbreviation's  variable
-              abbreviation goes.  Alternatively, a format can use the pair  of
+              part,   which   is   taken   from  the  LETTER/S  field  of  the
-              characters  %z  to  stand  for  the  UT offset in the form +-hh,
+              corresponding rule; any timestamps  that  precede  the  earliest
-              +-hhmm, or +-hhmmss, using the shortest form that does not  lose
+              rule  use the LETTER/S of the earliest standard-time rule (which
-              information,  where  hh,  mm, and ss are the hours, minutes, and
+              in this case must exist).  Alternatively, a format can  use  the
-              seconds east (+) or west (-) of UT.  Alternatively, a slash  (/)
+              pair  of  characters  %z  to stand for the UT offset in the form
-              separates  standard  and  daylight abbreviations.  To conform to
+              +-hh, +-hhmm, or +-hhmmss, using the shortest form that does not
-              POSIX, a time zone abbreviation should contain only alphanumeric
+              lose information, where hh, mm, and ss are the  hours,  minutes,
-              ASCII characters, "+" and "-".  By  convention,  the  time  zone
+              and  seconds east (+) or west (-) of UT.  Alternatively, a slash
-              abbreviation  "-00"  is  a  placeholder that means local time is
+              (/) separates standard and daylight abbreviations.   To  conform
-              unspecified.
+              to   POSIX,   a  time  zone  abbreviation  should  contain  only
+              alphanumeric ASCII characters, "+" and "-".  By convention,  the
+              time  zone  abbreviation "-00" is a placeholder that means local
+              time is unspecified.
 
        UNTIL  The time at which the UT offset or  the  rule(s)  change  for  a
               location.   It  takes the form of one to four fields YEAR [MONTH
@@ -369,7 +372,7 @@ FILES
          Rule    US    1967  1973  -  Apr  lastSun  2:00  1:00  D
          # Zone  NAME               STDOFF  RULES  FORMAT  [UNTIL]
          Zone    America/Menominee  -5:00   -      EST     1973 Apr 29 2:00
-                 -6:00              US      C%sT
+                                    -6:00   US     C%sT
 
        Here, an incorrect reading would be there were  two  clock  changes  on
        1973-04-29,  the first from 02:00 EST (-05) to 01:00 CST (-06), and the
@@ -421,14 +424,14 @@ FILES
        second time given by the other fields should be  interpreted  as  local
        (wall clock) time.
 
-       Rolling  leap  seconds  were  implemented  back  when  it was not clear
+       Rolling  leap  seconds  would let one see Times Square ball drops where
-       whether common practice was rolling or stationary, with  concerns  that
+       there'd be a "3... 2... 1... leap... Happy New Year" countdown, placing
-       one  would  see  Times  Square ball drops where there'd be a "3... 2...
+       the leap second at midnight New York time  rather  than  midnight  UTC.
-       1... leap... Happy New Year" countdown,  placing  the  leap  second  at
+       Although  stationary leap seconds are the common practice, rolling leap
-       midnight  New  York  time  rather  than  midnight  UTC.   However, this
+       seconds can be useful in specialized applications like SMPTE  timecodes
-       countdown style does not seem to have caught on,  which  means  rolling
+       that  may  prefer  to  put  leap second discontinuities at the end of a
-       leap  seconds are not used in practice; also, they are not supported if
+       local broadcast day.  However, rolling leap seconds are  not  supported
-       the -r option is used.
+       if the -r option is used.
 
        The expiration line, if present, has the form:
 
@@ -442,7 +445,7 @@ FILES
        in UTC for the leap second table.
 
 EXTENDED EXAMPLE
-       Here is an extended example of zic input, intended to  illustrate  many
+       Here  is  an extended example of zic input, intended to illustrate many
        of its features.
 
          # Rule  NAME  FROM  TO    -  IN   ON       AT    SAVE  LETTER/S
@@ -463,29 +466,29 @@ EXTENDED EXAMPLE
 
          Link    Europe/Zurich  Europe/Vaduz
 
-       In  this  example,  the EU rules are for the European Union and for its
+       In this example, the EU rules are for the European Union  and  for  its
-       predecessor organization, the European Communities.   The  timezone  is
+       predecessor  organization,  the  European Communities.  The timezone is
-       named  Europe/Zurich  and  it has the alias Europe/Vaduz.  This example
+       named Europe/Zurich and it has the alias  Europe/Vaduz.   This  example
-       says that Zurich was  34  minutes  and  8  seconds  east  of  UT  until
+       says  that  Zurich  was  34  minutes  and  8  seconds  east of UT until
-       1853-07-16  at 00:00, when the legal offset was changed to 7 degrees 26
+       1853-07-16 at 00:00, when the legal offset was changed to 7 degrees  26
-       minutes 22.50 seconds, which works out to 0:29:45.50; zic  treats  this
+       minutes  22.50  seconds, which works out to 0:29:45.50; zic treats this
-       by  rounding  it  to  0:29:46.  After 1894-06-01 at 00:00 the UT offset
+       by rounding it to 0:29:46.  After 1894-06-01 at  00:00  the  UT  offset
-       became one hour and Swiss daylight saving  rules  (defined  with  lines
+       became  one  hour  and  Swiss daylight saving rules (defined with lines
-       beginning  with  "Rule  Swiss")  apply.   From  1981 to the present, EU
+       beginning with "Rule Swiss") apply.   From  1981  to  the  present,  EU
-       daylight saving rules have applied, and the UTC offset has remained  at
+       daylight  saving rules have applied, and the UTC offset has remained at
        one hour.
 
        In 1941 and 1942, daylight saving time applied from the first Monday in
-       May  at 01:00 to the first Monday in October at 02:00.  The pre-1981 EU
+       May at 01:00 to the first Monday in October at 02:00.  The pre-1981  EU
-       daylight-saving rules  have  no  effect  here,  but  are  included  for
+       daylight-saving  rules  have  no  effect  here,  but  are  included for
        completeness.  Since 1981, daylight saving has begun on the last Sunday
-       in  March  at  01:00  UTC.   Until  1995  it  ended  the last Sunday in
+       in March at 01:00  UTC.   Until  1995  it  ended  the  last  Sunday  in
-       September at 01:00 UTC, but this changed to the last Sunday in  October
+       September  at 01:00 UTC, but this changed to the last Sunday in October
        starting in 1996.
 
-       For   purposes  of  display,  "LMT"  and  "BMT"  were  initially  used,
+       For  purposes  of  display,  "LMT"  and  "BMT"  were  initially   used,
-       respectively.  Since Swiss rules and later EU rules were  applied,  the
+       respectively.   Since  Swiss rules and later EU rules were applied, the
-       time  zone  abbreviation  has  been  CET for standard time and CEST for
+       time zone abbreviation has been CET for  standard  time  and  CEST  for
        daylight saving time.
 
 FILES
@@ -496,15 +499,15 @@ FILES
               Default timezone information directory.
 
 NOTES
-       For areas with more than two types of local time, you may need  to  use
+       For  areas  with more than two types of local time, you may need to use
-       local  standard  time in the AT field of the earliest transition time's
+       local standard time in the AT field of the earliest  transition  time's
-       rule to ensure that  the  earliest  transition  time  recorded  in  the
+       rule  to  ensure  that  the  earliest  transition  time recorded in the
        compiled file is correct.
 
-       If,  for  a particular timezone, a clock advance caused by the start of
+       If, for a particular timezone, a clock advance caused by the  start  of
-       daylight saving coincides with and is equal to a clock  retreat  caused
+       daylight  saving  coincides with and is equal to a clock retreat caused
-       by  a change in UT offset, zic produces a single transition to daylight
+       by a change in UT offset, zic produces a single transition to  daylight
-       saving at the new UT offset without any change in  local  (wall  clock)
+       saving  at  the  new UT offset without any change in local (wall clock)
        time.  To get separate transitions use multiple zone continuation lines
        specifying transition instants using universal time.
 

zic.c

@@ -470,7 +470,7 @@ size_overflow(void)
   memory_exhausted(_("size overflow"));
 }
 
-ATTRIBUTE_REPRODUCIBLE static ptrdiff_t
+ATTRIBUTE_PURE_114833 static ptrdiff_t
 size_sum(size_t a, size_t b)
 {
 #ifdef ckd_add
@@ -484,7 +484,7 @@ size_sum(size_t a, size_t b)
   size_overflow();
 }
 
-ATTRIBUTE_REPRODUCIBLE static ptrdiff_t
+ATTRIBUTE_PURE_114833 static ptrdiff_t
 size_product(ptrdiff_t nitems, ptrdiff_t itemsize)
 {
 #ifdef ckd_mul
@@ -499,7 +499,7 @@ size_product(ptrdiff_t nitems, ptrdiff_t itemsize)
   size_overflow();
 }
 
-ATTRIBUTE_REPRODUCIBLE static ptrdiff_t
+ATTRIBUTE_PURE_114833 static ptrdiff_t
 align_to(ptrdiff_t size, ptrdiff_t alignment)
 {
   ptrdiff_t lo_bits = alignment - 1, sum = size_sum(size, lo_bits);
@@ -523,7 +523,7 @@ memcheck(void *ptr)
 	return ptr;
 }
 
-ATTRIBUTE_MALLOC static void *
+static void *
 emalloc(size_t size)
 {
   return memcheck(malloc(size));
@@ -535,7 +535,7 @@ erealloc(void *ptr, size_t size)
   return memcheck(realloc(ptr, size));
 }
 
-ATTRIBUTE_MALLOC static char *
+static char *
 estrdup(char const *str)
 {
   return memcheck(strdup(str));
@@ -1435,7 +1435,7 @@ relname(char const *target, char const *linkname)
 /* Return true if A and B must have the same parent dir if A and B exist.
    Return false if this is not necessarily true (though it might be true).
    Keep it simple, and do not inspect the file system.  */
-static bool
+ATTRIBUTE_PURE_114833 static bool
 same_parent_dirs(char const *a, char const *b)
 {
   for (; *a == *b; a++, b++)
@@ -2982,10 +2982,10 @@ rule_cmp(struct rule const *a, struct rule const *b)
 	return a->r_dayofmonth - b->r_dayofmonth;
 }
 
-/* Store into RESULT a POSIX.1-2017 TZ string that represent the future
+/* Store into RESULT a proleptic TZ string that represent the future
    predictions for the zone ZPFIRST with ZONECOUNT entries.  Return a
    compatibility indicator (a TZDB release year) if successful, a
-   negative integer if no such TZ string exissts.  */
+   negative integer if no such TZ string exists.  */
 static int
 stringzone(char *result, struct zone const *zpfirst, ptrdiff_t zonecount)
 {
@@ -3177,8 +3177,7 @@ outzone(const struct zone *zpfirst, ptrdiff_t zonecount)
 	if (noise) {
 		if (!*envvar)
 			warning("%s %s",
-				_("no POSIX.1-2017 environment variable"
+				_("no proleptic TZ string for zone"),
-				  " for zone"),
 				zpfirst->z_name);
 		else if (compat != 0) {
 			/* Circa-COMPAT clients, and earlier clients, might
@@ -3442,7 +3441,7 @@ outzone(const struct zone *zpfirst, ptrdiff_t zonecount)
 	if (do_extend) {
 		/*
 		** If we're extending the explicitly listed observations for
-		** 400 years because we can't fill the POSIX.1-2017 TZ field,
+		** 400 years because we can't fill the proleptic TZ field,
 		** check whether we actually ended up explicitly listing
 		** observations through that period.  If there aren't any
 		** near the end of the 400-year period, add a redundant
@@ -3627,7 +3626,7 @@ lowerit(char a)
 }
 
 /* case-insensitive equality */
-ATTRIBUTE_REPRODUCIBLE static bool
+ATTRIBUTE_PURE_114833 static bool
 ciequal(register const char *ap, register const char *bp)
 {
 	while (lowerit(*ap) == lowerit(*bp++))
@@ -3636,7 +3635,7 @@ ciequal(register const char *ap, register const char *bp)
 	return false;
 }
 
-ATTRIBUTE_REPRODUCIBLE static bool
+ATTRIBUTE_PURE_114833 static bool
 itsabbr(register const char *abbr, register const char *word)
 {
 	if (lowerit(*abbr) != lowerit(*word))
@@ -3652,7 +3651,7 @@ itsabbr(register const char *abbr, register const char *word)
 
 /* Return true if ABBR is an initial prefix of WORD, ignoring ASCII case.  */
 
-ATTRIBUTE_REPRODUCIBLE static bool
+ATTRIBUTE_PURE_114833 static bool
 ciprefix(char const *abbr, char const *word)
 {
   do
@@ -3762,7 +3761,7 @@ time_overflow(void)
   exit(EXIT_FAILURE);
 }
 
-ATTRIBUTE_REPRODUCIBLE static zic_t
+ATTRIBUTE_PURE_114833 static zic_t
 oadd(zic_t t1, zic_t t2)
 {
 #ifdef ckd_add
@@ -3776,7 +3775,7 @@ oadd(zic_t t1, zic_t t2)
   time_overflow();
 }
 
-ATTRIBUTE_REPRODUCIBLE static zic_t
+ATTRIBUTE_PURE_114833 static zic_t
 tadd(zic_t t1, zic_t t2)
 {
 #ifdef ckd_add