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Are time slots diverse with the same GMT offset?

Windows asks users to choose from 200 time zones , when there are actually only 25 GMT offsets. (see below)

Can I ask users in my application to select one of them? Is there a difference between time zones that have the same GMT offset? ( for example: Mountain Standard Time vs Mexico Standard Time 2)

-12.0,GMT -12:00,Eniwetok, Kwajalein -11.0,GMT -11:00,Midway Island, Samoa -10.0,GMT -10:00,Hawaii -9.0,GMT -9:00,Alaska -8.0,GMT -8:00,Pacific Time, US & Canada -7.0,GMT -7:00,Mountain Time, US & Canada -6.0,GMT -6:00,Central Time, US & Canada, Mexico City -5.0,GMT -5:00,Eastern Time, US & Canada, Bogota, Lima -4.0,GMT -4:00,Atlantic Time, Canada, Caracas, La Paz -3.5,GMT -3:30,Newfoundland -3.0,GMT -3:00,Brazil, Buenos Aires, Georgetown -2.0,GMT -2:00,Mid-Atlantic -1.0,GMT -1:00 hour,Azores, Cape Verde Islands 0.0,GMT,Western Europe Time, London, Lisbon, Casablanca 1.0,GMT +1:00 hour,Brussels, Copenhagen, Madrid, Paris 2.0,GMT +2:00,Kaliningrad, South Africa 3.0,GMT +3:00,Baghdad, Riyadh, Moscow, St. Petersburg 3.5,GMT +3:30,Tehran 4.0,GMT +4:00,Abu Dhabi, Muscat, Baku, Tbilisi 4.5,GMT +4:30,Kabul 5.0,GMT +5:00,Ekaterinburg, Islamabad, Karachi, Tashkent 5.5,GMT +5:30,Bombay, Calcutta, Madras, New Delhi 5.75,GMT +5:45,Kathmandu 6.0,GMT +6:00,Almaty, Dhaka, Colombo 7.0,GMT +7:00,Bangkok, Hanoi, Jakarta 8.0,GMT +8:00,Beijing, Perth, Singapore, Hong Kong 9.0,GMT +9:00,Tokyo, Seoul, Osaka, Sapporo, Yakutsk 9.5,GMT +9:30,Adelaide, Darwin 10.0,GMT +10:00,Eastern Australia, Guam, Vladivostok 11.0,GMT +11:00,Magadan, Solomon Islands, New Caledonia 12.0,GMT +12:00,Auckland, Wellington, Fiji, Kamchatka
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2 answers

In general, no, you cannot. The time zone differs not only by default GMT offset, but also DST (daylight saving time). Thus, two TZs may have the same offset, but one with DST and the other without. Even TZs with the same offset and both with DST may differ at the beginning and end of the DST.

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You should also consider DST. From your list:

 -5.0,GMT -5:00,Eastern Time, US & Canada, Bogota, Lima

In Lima and New York, one hour falls in the summer. See http://www.timeanddate.com/worldclock/

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Source: https://habr.com/ru/post/1413473/

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