[tz] Idea for internationalized time point unique time zone abbreviations
dpatte at relativedata.com
Wed Jun 6 00:09:07 UTC 2012
Good idea, but no one has the right to impose a system like this on any
country. Time zones and their names are decided at national, regional,
and even local government levels, in some cases. The tz database simply
tries to capture current tz usage - not apply or impose a standard.
On 2012-06-05 18:42, Tobias Conradi wrote:
> == INTRODUCTION ==
> If time zone abbreviations for a given point in time are unique they
> can be used to faster find IANA time zones. The current abbreviations
> are not unique, e.g. IST could stand for Indian Standard Time and for
> Israel Standard Time.
> Since the IANA time zone database cutoff point is 1970-01-01T00:00:00Z
> and the first publication of ISO 3166 alpha-2 country codes occurred
> in the early 1970s, one could easily use the country codes to separate
> sets of abbreviations between countries.
> One rule sometimes used in the IANA time zone database for creating
> new abbreviations is to use the ISO alpha-2 country codes. The idea
> presented here applies such a rule rigidly.
> Apart from that the idea presented also applies rigid rules for
> marcation of offset changes like daylight saving time.
> == Features ==
> One can derive the country of the time zone to which the abbreviation
> belongs from the abbreviation and from knowledge of the current ISO
> country code for that country. This is not possible with current IANA
> time zone database abbreviations like CET, IST, EDT, GALT, EAST, CT
> (e.g. Cuba Time), CUT (1924 Central Ukraine Time).
> One can group the abbreviations by country, alone by alphabetic
> sorting of the abbreviations. This is not possible with current IANA
> time zone database abbreviations like CST (US), CT (Cuba), PST (US).
> If the year is known, one can identify the time zone for any given
> abbreviation. This is not possible with current IANA time zone
> database abbreviations like IST.
> Reduces the number of IANA time zones for some abbreviations, e.g. IST
> is used for Asia/Jerusalem, Asia/Kolkata, while INCT/INZT would only
> refer to Asia/Kolkata.
> == DEFINITIONS ==
> === D0) General ===
> D0.1) DST - Daylight saving time
> D0.2) Format: "<CC><LC><(OC)>T" #abbreviations would be four or five
> letters long. Details in D1 to D4.
> === D1) CC - country code and similar ===
> - ISO alpha-2 country code or,
> - a special code like "EU" or,
> - a code from the private use area to define larger regions, e.g.:
> -- XA - ASEAN
> -- XE - "East" for UTC offsets zones having positive offset
> -- XW - "West" for UTC offsets zones having negative offset
> -- ZZ - the whole world, used for UTC and UTC offset zones, details
> see examples.
> === D2) LC - location code and similar ===
> D2.1) A character from the set [A-Z], unique for each real time zone
> within the country. Preferably not from the set [SDF] or any letter
> agreed in D3 for offset changes
> D2.2) A character from the set [0-9] for numbered zones, e.g. in Russia.
> D2.3) The letter C (Common Time) for the most common time, maybe also
> N derived from "National Time".
> D2.4) The letter Z could be used if there is only one time zone. Could
> be dropped for countries that only have one zone, but mandatory per
> D2.5) For UTC offset zones that start with ZZ, when using date-time
> group (DTG) letters, the letter G - not the letter L to make changing
> into or from E harder. Otherwise either E for East or W for West, as
> defined in D1.
> === D3) OC - seasonal offset code and similar ===
> D3.1) for DST a letter from the set [SD], preferably "D" since "S" in
> some contexts stands for "standard time"
> So even if in Europe the term "summer time" is more common, the
> preferred presentation uses unambiguous"D"
> D3.2) For wartime maybe the letter W or F as in forward time, W in D2
> stands for West.
> D3.3) For double summer time - to be defined, maybe M for midsummer time
> D3.4) For absence of any extra rules "standard time", the letter Z is optional.
> D3.5) For UTC offset zones: a digit.
> === D4) T ===
> As currently done in English to indicate "Time".
> == EXAMPLES ==
> === E1) No DST ===
> CUCT - Cuba (Common) Time#in IANA tzdb northamerica 8.54 is CT
> THCT - Thailand (Common) Time
> USET - US Eastern Time
> USCT - US Central Time
> USPT - US Pacific Time
> CAET - Canada Eastern Time
> CLCT - Chile (Common) Time #Continental Time
> CLET - Chile Eastern Time #Easter Islands, which in the IANA tzdb is EAS%sT
> ECCT - Ecuador (Common) Time #Continental Time
> ECGT - Galapagos Time #which in the IANA tzdb is GALT
> RUOT - Omsk Time #in IANA tzdb is OMST, could be read as Oman
> Summer/Standard Time
> RUMT - Moscow Time #Maybe RUCT - Russia Central/Common Time or RUNT -
> Russia National Time
> RUKT - Kaliningrad Time
> RUIT - Irkutsk Time
> RUVT - Volgograd Time #in IANA tzdb was VOLT
> Optional: RU1T - Russia First Time Zone
> Optional: RU2T - Russia Second Time Zone
> EUCT - Central European Time #Some countries that use this time, are
> not in the EU.
> EUWT - Western European Time #See comment for EUCT
> EUET - Eastern European Time #See comment for EUCT
> XACT - ASEAN Common Time
> XE01T - UTC+01
> XE08T - UTC+08
> XE13T - UTC+13
> XW06T - UTC-06
> XW11T - UTC-11
> ZZZT - UTC
> ZZE1T - UTC+01
> ZZE8T - UTC+08
> ZZEAT - UTC+10 # A = hexadecimal for 10
> ZZEDT - UTC+13 # A = hexadecimal for 13
> ZZW6T - UTC-06
> ZZWBT - UTC-11 # B = hexadecimal for 11
> #Letters from the NATO(?) date-time group
> #taken from http://de.wikipedia.org/wiki/Date_Time_Group
> ZZGZT - UTC±00
> ZZGAT - UTC+01
> ZZGHT - UTC+08
> ZZGKT - UTC+10
> ZZGST - UTC-06
> ZZGXT - UTC-11
> === E2) With DST ===
> #for meaning of the third letter see section E2
> RUMDT # Daylight saving time or "decree time"
> EUCDT #preferred as defined in D3.1
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