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2016-04-10 20:33:38 by Henrik Grubbström (Grubba) <>

Updated to tzdata2016c.

173:   Here are the general rules used for choosing time zone abbreviations,   in decreasing order of importance:    -  Use abbreviations that consist of three or more ASCII letters. +  Use three or more characters that are ASCII alphanumerics or '+' or '-'.    Previous editions of this database also used characters like    ' ' and '?', but these characters have a special meaning to    the shell and cause commands like
181:    to have unexpected effects.    Previous editions of this rule required upper-case letters,    but the Congressman who introduced Chamorro Standard Time -  preferred "ChST", so the rule has been relaxed. -  -  This rule guarantees that all abbreviations could have -  been specified by a POSIX TZ string. POSIX -  requires at least three characters for an -  abbreviation. POSIX through 2000 says that an abbreviation -  cannot start with ':', and cannot contain ',', '-', -  '+', NUL, or a digit. POSIX from 2001 on changes this -  rule to say that an abbreviation can contain only '-', '+', +  preferred "ChST", so lower-case letters are now allowed. +  Also, POSIX from 2001 on relaxed the rule to allow '-', '+',    and alphanumeric characters from the portable character set -  in the current locale. To be portable to both sets of -  rules, an abbreviation must therefore use only ASCII -  letters. +  in the current locale. In practice ASCII alphanumerics and +  '+' and '-' are safe in all locales.    -  +  In other words, in the C locale the POSIX extended regular +  expression [-+[:alnum:]]{3,} should match the abbreviation. +  This guarantees that all abbreviations could have been +  specified by a POSIX TZ string. +     Use abbreviations that are in common use among English-speakers,    e.g. 'EST' for Eastern Standard Time in North America.    We assume that applications translate them to other languages