<font size=2 face="sans-serif">> So just to be clear, CLDR *could*
support a Europe/Dublin that had <br>> an independent metazone with <standard>Irish Standard Time</<br>> standard><daylight>Greenwich Mean Time</daylight>,
it's just that <br>> synchronizing such a change with the tzdb change is intractable, right?<br>> <br>> (that version number field is looking more and more important...)<br>> <br></font><br><font size=2 face="sans-serif">If we need a single TZ DB zone has changing
names time to time, we create</font><br><font size=2 face="sans-serif">what we call "meta zone",
and define a set of short/long - standard/daylight</font><br><font size=2 face="sans-serif">/generic name for the meta zone.</font><br><br><font size=2 face="sans-serif">For example,</font><br><br><font size=2 face="sans-serif">----</font><br><font size=2 face="sans-serif">Zone America/North_Dakota/Center -6:45:12
- LMT 1883 Nov 18 12:14:48</font><br><font size=2 face="sans-serif">
-7:00
US M%sT
1992 Oct 25 2:00</font><br><font size=2 face="sans-serif">
-6:00
US C%sT</font><br><font size=2 face="sans-serif">----</font><br><br><font size=2 face="sans-serif">CLDR define meta zones </font><br><br><font size=2 face="sans-serif"> <metazone
type="America_Central"></font><br><font size=2 face="sans-serif"> <long></font><br><font size=2 face="sans-serif"> <generic>Central
Time</generic></font><br><font size=2 face="sans-serif"> <standard>Central
Standard Time</standard></font><br><font size=2 face="sans-serif"> <daylight>Central
Daylight Time</daylight></font><br><font size=2 face="sans-serif"> </long></font><br><font size=2 face="sans-serif"> <short></font><br><font size=2 face="sans-serif"> <generic>CT</generic></font><br><font size=2 face="sans-serif"> <standard>CST</standard></font><br><font size=2 face="sans-serif"> <daylight>CDT</daylight></font><br><font size=2 face="sans-serif"> </short></font><br><font size=2 face="sans-serif"> </metazone></font><br><br><font size=2 face="sans-serif"> <metazone
type="America_Mountain"></font><br><font size=2 face="sans-serif"> <long></font><br><font size=2 face="sans-serif"> <generic>Mountain
Time</generic></font><br><font size=2 face="sans-serif"> <standard>Mountain
Standard Time</standard></font><br><font size=2 face="sans-serif"> <daylight>Mountain
Daylight Time</daylight></font><br><font size=2 face="sans-serif"> </long></font><br><font size=2 face="sans-serif"> <short></font><br><font size=2 face="sans-serif"> <generic>MT</generic></font><br><font size=2 face="sans-serif"> <standard>MST</standard></font><br><font size=2 face="sans-serif"> <daylight>MDT</daylight></font><br><font size=2 face="sans-serif"> </short></font><br><font size=2 face="sans-serif"> </metazone></font><br><br><font size=2 face="sans-serif">These meta zone display names are translated
for various locales.</font><br><br><font size=2 face="sans-serif">Then, we have historic zone -> meta
zone mapping data as below:</font><br><br><font size=2 face="sans-serif"> <timezone
type="America/North_Dakota/Center"></font><br><font size=2 face="sans-serif"> <usesMetazone
to="1992-10-25 08:00" mzone="America_Mountain"/></font><br><font size=2 face="sans-serif"> <usesMetazone
from="1992-10-25 08:00" mzone="America_Central"/></font><br><font size=2 face="sans-serif"> </timezone></font><br><br><br><font size=2 color=#600000 face="sans-serif">So, when CLDR consumer
code such as ICU want to show time zone display name</font><br><font size=2 color=#600000 face="sans-serif">at a given time, it looks
up which meta zone is used at the time, then check standard</font><br><font size=2 color=#600000 face="sans-serif">or daylight, then retrieve
appropriate display name data type.</font><br><br><font size=2 color=#600000 face="sans-serif">With above example, if
the input time is 2018-01-01T00:00:00Z, then meta zone</font><br><font size=2 color=#600000 face="sans-serif">"America_Central"
is resolved with the meta zone mapping data above. ICU uses</font><br><font size=2 color=#600000 face="sans-serif">data generated from tz
database and detect the date fall into standard time. Then</font><br><font size=2 color=#600000 face="sans-serif">zone name for standard
in meta zone "America_Central" is used.</font><br><br><br><font size=2 color=#600000 face="sans-serif">At this moment, "Irish
Standard Time" is set to zone directly, but if we need more</font><br><font size=2 color=#600000 face="sans-serif">historic names, we can
create a new meta zone, define a set of name there, and add</font><br><font size=2 color=#600000 face="sans-serif">it to zone-to-meta-zone
mapping data.</font><br><br><br><font size=2 color=#600000 face="sans-serif">-Yoshito</font><br><BR>