The data are from https://www.timeanddate.com/library/abbreviations/timezones/ and were hand-edited to develop this code, so there may be errors. Also, note that some of these contradict; if you examine the code, you'll see some commented-out portions that represent solving conflicting definitions by choosing the more common timezone abbreviation over a the less common one.
a timezone, e.g.
Number of hours in offset, e.g.
AST yields 4.
#> Atlantic Standard Time is 4 hours after UTC