Time Zone Data Reorganization
Existing Data by Type
a) alias mapping
supplementalData.xml
<zoneFormatting>
...
<zoneItem type="Africa/Asmera" territory="ER" aliases="Africa/Asmara"/>
...
</zoneFormatting>
b) metazone -> golden zone
supplementalData.xml
<mapTimezones type="metazone">
...
<mapZone other="Africa_Central" territory="001" type="Africa/Maputo"/>
<mapZone other="Africa_Central" territory="BI" type="Africa/Bujumbura"/>
<mapZone other="Africa_Central" territory="BW" type="Africa/Gaborone"/>
<mapZone other="Africa_Central" territory="CD" type="Africa/Lubumbashi"/>
<mapZone other="Africa_Central" territory="MW" type="Africa/Blantyre"/>
<mapZone other="Africa_Central" territory="RW" type="Africa/Kigali"/>
<mapZone other="Africa_Central" territory="ZM" type="Africa/Lusaka"/>
<mapZone other="Africa_Central" territory="ZW" type="Africa/Harare"/>
...
</mapTimezones>
c) historic metazone mapping
metazoneInfo.xml
<metazoneInfo>
...
<timezone type="Asia/Yerevan">
<usesMetazone to="1991-09-22 20:00" mzone="Yerevan"/>
<usesMetazone from="1991-09-22 20:00" mzone="Armenia"/>
</timezone>
...
</metazoneInfo>
d) zone -> territory
supplementalData.xml
<zoneFormatting>
...
<zoneItem type="Africa/Asmera" territory="ER" aliases="Africa/Asmara"/>
...
</zoneFormatting>
e) territories where multiple time zones are available
supplementalData.xml
<zoneFormatting multizone="001 AQ AR AU BR CA CD CL CN EC ES FM GL ID KI KZ MH MN MX MY NZ PF PT RU UA UM US UZ" tzidVersion="2009f">
f) Mapping between Olson ID and Unicode time zone short ID (bcp47 ids)
(1) bcp47/timezone.xml
Short ID -> Olson ID
<type name="adalv" alias="Europe/Andorra"/>
(2) supplementalData.xml
Olson ID -> Short ID
<bcp47KeywordMappings>
...
<mapTypes type="timezone">
...
<typeMap type="Europe/Andorra" bcp47="adalv"/>
...
</mapTypes>
...
</bcp47KeywordMappings>
g) Windows tzid mapping
supplementalData.xml
<mapTimezones type="windows">
<mapZone other="AUS Central Standard Time" type="Australia/Darwin"/> <!-- S (GMT+09:30) Darwin -->
...
</mapTimezones>
Hige Level Proposal
- bcp47/timezone.xml must be there, because all keyword keys/types must reside in bcp47/*.xml. Therefore, f) (2) <bcpKeywordMappings> should be deprecated (this is an invert mapping table)
- The set of canonical Unicode time zone IDs is defined by bcp47/timezone.xml. Because we do not want to maintain the set in multiple places, long ID aliases could be embedded in bcp47/timezone.xml.
- Metazone tables (b and c) should be in a single file
- Territory mapping is almost equivalent to zone.tab in tzdata (minor exception - zone.tab does not include deprecated zones). I think it is not worth maintaining the data in CLDR. Therefore, d) and e) should be deprecated / no corresponding data in 1.8
- Windows tz mapping is independently maintained - it should be moved into a new file. Side note: A single Windows tz could be mapped to multiple zones in future.
New Data Organization
1. bcp47/timezone.xml
Add long aliases - for example
<type name="erasm" alias="Africa/Asmera Africa/Asmara"/>
2. metazoneInfo.xml
Add b) into this file
3. wintz.xml (new)
Store only g).