On Sun, Oct 16, 2016, at 23:55, Gabriel Gaspar via tz wrote:
Hello there, and sorry for the intrusion.
I presently write to this list with a suggestion for addition of an entry in the time zone database, America/Brasilia, or at least for a clarification on why there may not be one. Being the standard official time in Brazil, I firmly believe there should be one such entry (unless, of course, matters of greater power disallow it).
This is essentially the same as the Beijing/Shanghai problem that has been discussed before - the policy is that the timezone name in the timezone database is based on the largest city that the timezone applies to, regardless of the existence of another city which may be part of a popular or official name of the same time zone. Thus China's timezone is "Asia/Shanghai" despite being called "Beijing Time". This is considered acceptable because the raw timezone name is not supposed to be displayed to users; the string meant to be displayed to users is the description in zone.tab, which is "Brazil (southeast: GO, DF, MG, ES, RJ, SP, PR, SC, RS)" for America/Sao_Paulo. For its part, Asia/Shanghai's description is "east China - Beijing, Guangdong, Shanghai, etc." Perhaps Asia/Sao_Paulo should likewise be "southeast Brazil - Brasília, Rio de Janeiro, São Paulo, etc." and leave the precise enumeration of states to the shapefile project. It's also worth noting that timezones in the timezone database don't generally correspond one-to-one with civil timezones, but subdivide them based on regions within a timezone that used to be in a different civil timezone before the present day but after 1970, or have or had different rules for daylight saving time. For example, Mato Grosso and Mato Grosso do Sol have different timezones (America/Cuiaba and America/Campo_Grande, respectively), because the former did not observe daylight saving time in 2003-2004. In all, there are sixteen timezones applying to various parts of Brazil, and it's simply good fortune that there is (so far as I can tell) only one that applies to the whole section of UTC-3:00 that presently observes daylight saving time. Out of curiosity, are the northern parts of UTC-3:00 that do not observe daylight saving time (Bahia, Fortaleza, etc) also considered "Brasilia Time"? Or for only part of the year, and the rest it is "Brasilia time -1", when they're not the ones whose clocks have changed [and then presumably Fernando de Noronha, whose clocks also do not change, is "Brasilia time" for part of the year]? How should this be differentiated if this name is used?