The BC government is considering recommending the abbreviation “PacT”
for Pacific Time as observed in British Columbia since 2026-03-09. Two
draft TZDB patches are attached that would implement this. The first
simply changes “MST” to “PacT” for timestamps starting 2026-11-01, in
line with 2026b’s temporary hack to delay this transition because the
downstream user CLDR v48.2 (2026-03-17) cannot support BC’s current
timekeeping. The second patch removes the temporary hack, adjusting TZDB
to better reflect BC’s timekeeping, in the hope that the temporary hack
is no longer needed once the abbreviation changes from “MST” to “PacT”.
I have not installed these patches into the TZDB development repository,
as “PacT” is still under consideration. Comments are welcome as usual.From 42fb2dfdfbed9393253a8b89f8a58109de38f338 Mon Sep 17 00:00:00 2001
From: Paul Eggert <[email protected]>
Date: Mon, 4 May 2026 21:57:17 -0700
Subject: [PATCH 1/2] PacT, not MST, for America/Vancouver abbreviation
* NEWS: Mention this.
* northamerica (America/Vancouver): Use PacT instead of MST as the
time zone abbreviation starting 2026-11-01.
---
NEWS | 16 ++++++++++++++++
northamerica | 23 ++++++-----------------
2 files changed, 22 insertions(+), 17 deletions(-)
diff --git a/NEWS b/NEWS
index fb1ced71..538bb1fd 100644
--- a/NEWS
+++ b/NEWS
@@ -1,5 +1,21 @@
News for the tz database
+Unreleased, experimental changes
+
+ Briefly:
+ Use “PacT” for British Columbia time starting 2026-11-01.
+
+ Changes to past and future time zone abbreviations
+
+ British Columbia is considering using “PacT” to abbreviate its
+ legal time starting 2026-03-09. This experimental patch implements
+ this suggestion. However, in keeping with 2026b’s temporary hack
+ for CLDR v48.2 (2026-03-17), this experimental patch changes the
+ abbreviation starting with 2026-11-01 timestamps. Once CLDR is
+ fixed and we remove 2026b’s temporary hack, the “PacT”
+ abbreviation can also start on 2026-03-09.
+
+
Release 2026b - 2026-04-22 23:06:43 -0700
Briefly:
diff --git a/northamerica b/northamerica
index 3e8641e1..853786f1 100644
--- a/northamerica
+++ b/northamerica
@@ -1962,13 +1962,13 @@ Zone America/Edmonton -7:33:52 - LMT 1906 Sep
# on March 8 will be the last time change, ending twice-yearly clock changes.”
# https://news.gov.bc.ca/releases/2026AG0013-000209
#
-# From Paul Eggert (2026-03-07):
+# From Paul Eggert (2026-05-04):
# The law says that 21 hours after the usual 2026-03-08 02:00 switch from
# PST to PDT, the next day inaugurates the new standard time Pacific Time,
# i.e., just one clock change but two name changes separated by 21 hours.
# PT, the obvious abbreviation for Pacific Time, is one letter too short
# to conform to TZDB’s (and POSIX’s) [-+[:alnum:]]{3,6} requirements.
-# I asked the BC government for advice, with no response. For now, do this:
+# For now, do this:
# 1. As a temporary hack, pretend that the BC law takes effect
# not on 2026-03-09 at 00:00, but on 2026-11-01 at 02:00.
# This pretense works around a limitation in CLDR v48.2 (2026-03-17),
@@ -1978,20 +1978,9 @@ Zone America/Edmonton -7:33:52 - LMT 1906 Sep
# standard time, but it does have the right UT offset and it
# works around the CLDR limitation. We should be able to remove
# the temporary hack after CLDR is fixed.
-# 2. After the BC law takes effect, model the time as MST sans DST.
-# We can change this later if another conforming non-numeric abbreviation
-# for Pacific Time becomes more popular. Possibilities include:
-# MST - the most compatible with existing software and practice,
-# and already used in parts of BC and in Yukon
-# PDT - almost as software-friendly, but confusing because it implies
-# it is DST and is paired with PST, whereas PT is standard time
-# PST - straightforward but even more confusing,
-# and will likely break much software that assumes PST is -08
-# -07 - accurate and clear in itself, but makes BC look odd vs neighbors
-# CPT, CPST - for Canadian Pacific (Standard) Time,
-# by analogy with AEST in Australia
-# P-T - conforming approximation to “PT”
-# PT+ - like P-T but suggesting one-hour advance over PST
+# 2. After the BC law takes effect, model the time as PacT sans DST.
+# The abbreviation “PacT” is currently being considered by the
+# BC government.
# From Chris Walton (2026-03-15):
# The Regional District of East Kootenay is planning to move to year-round
@@ -2024,7 +2013,7 @@ Zone America/Vancouver -8:12:28 - LMT 1884
# Temporary hack; see above.
-8:00 1:00 PDT 2026 Nov 1 02:00
# End of temporary hack.
- -7:00 - MST
+ -7:00 - PacT
Zone America/Dawson_Creek -8:00:56 - LMT 1884
-8:00 Canada P%sT 1947
-8:00 Vanc P%sT 1972 Aug 30 2:00
--
2.54.0
From de9868d31a5b45aaa9f0dc86f458ae3f4bcf7068 Mon Sep 17 00:00:00 2001
From: Paul Eggert <[email protected]>
Date: Mon, 4 May 2026 22:03:15 -0700
Subject: [PATCH 2/2] Remove temporary hack for CLDR v48.2
* NEWS: Mention this.
* northamerica: Remove temporary hack that was useful for CLDR v48.2.
---
NEWS | 10 ++++------
northamerica | 20 ++------------------
2 files changed, 6 insertions(+), 24 deletions(-)
diff --git a/NEWS b/NEWS
index 538bb1fd..283bcfbc 100644
--- a/NEWS
+++ b/NEWS
@@ -3,17 +3,15 @@ News for the tz database
Unreleased, experimental changes
Briefly:
- Use “PacT” for British Columbia time starting 2026-11-01.
+ Use “PacT” for British Columbia time starting 2026-03-09.
Changes to past and future time zone abbreviations
British Columbia is considering using “PacT” to abbreviate its
legal time starting 2026-03-09. This experimental patch implements
- this suggestion. However, in keeping with 2026b’s temporary hack
- for CLDR v48.2 (2026-03-17), this experimental patch changes the
- abbreviation starting with 2026-11-01 timestamps. Once CLDR is
- fixed and we remove 2026b’s temporary hack, the “PacT”
- abbreviation can also start on 2026-03-09.
+ this suggestion. It also removes the temporary hack needed for
+ CLDR v48.2 (2026-03-17), as CLDR should now be able to accommodate
+ BC timekeeping.
Release 2026b - 2026-04-22 23:06:43 -0700
diff --git a/northamerica b/northamerica
index 853786f1..8ec1e2a8 100644
--- a/northamerica
+++ b/northamerica
@@ -1966,21 +1966,8 @@ Zone America/Edmonton -7:33:52 - LMT 1906 Sep
# The law says that 21 hours after the usual 2026-03-08 02:00 switch from
# PST to PDT, the next day inaugurates the new standard time Pacific Time,
# i.e., just one clock change but two name changes separated by 21 hours.
-# PT, the obvious abbreviation for Pacific Time, is one letter too short
-# to conform to TZDB’s (and POSIX’s) [-+[:alnum:]]{3,6} requirements.
-# For now, do this:
-# 1. As a temporary hack, pretend that the BC law takes effect
-# not on 2026-03-09 at 00:00, but on 2026-11-01 at 02:00.
-# This pretense works around a limitation in CLDR v48.2 (2026-03-17),
-# which would otherwise say the interval uses “Pacific Standard Time”.
-# (Below, this temporary hack is marked “Temporary hack; see above.”)
-# Strictly speaking this hack is incorrect since the interval uses
-# standard time, but it does have the right UT offset and it
-# works around the CLDR limitation. We should be able to remove
-# the temporary hack after CLDR is fixed.
-# 2. After the BC law takes effect, model the time as PacT sans DST.
-# The abbreviation “PacT” is currently being considered by the
-# BC government.
+# After the BC law takes effect, model the time as PacT sans DST.
+# The abbreviation “PacT” is currently being considered by the BC government.
# From Chris Walton (2026-03-15):
# The Regional District of East Kootenay is planning to move to year-round
@@ -2010,9 +1997,6 @@ Rule Vanc 1962 2006 - Oct lastSun 2:00 0 S
Zone America/Vancouver -8:12:28 - LMT 1884
-8:00 Vanc P%sT 1987
-8:00 Canada P%sT 2026 Mar 9
- # Temporary hack; see above.
- -8:00 1:00 PDT 2026 Nov 1 02:00
- # End of temporary hack.
-7:00 - PacT
Zone America/Dawson_Creek -8:00:56 - LMT 1884
-8:00 Canada P%sT 1947
--
2.54.0
