Why do we need isDst as separate property?

README.md

Time zone daylight savings change using the same time zone offset (i.e., reason why https://github.com/rxaviers/iana-tz-data uses isDst)

This is based on https://github.com/rxaviers/iana-tz-data/commit/9a553608d0d6a4e40c09f8936bf66861c67755df

(WIP document)

America/Argentina/{Buenos_Aires, Catamarca, *} @1999

/usr/share/zoneinfo/America/Argentina/Buenos_Aires Sun Oct 3 02:59:59 1999 UTC = Sat Oct 2 23:59:59 1999 -03 isdst=0 /usr/share/zoneinfo/America/Argentina/Buenos_Aires Sun Oct 3 03:00:00 1999 UTC = Sun Oct 3 00:00:00 1999 -03 isdst=1

new Date(938919600000)

Antarctica/Palmer @2016

/usr/share/zoneinfo/Antarctica/Palmer Sun Dec 4 02:59:59 2016 UTC = Sat Dec 3 23:59:59 2016 -03 isdst=1 /usr/share/zoneinfo/Antarctica/Palmer Sun Dec 4 03:00:00 2016 UTC = Sun Dec 4 00:00:00 2016 -03 isdst=0

new Date(1480820400000)

Asia/Almaty @1991

/usr/share/zoneinfo/Asia/Almaty Sat Mar 30 19:59:59 1991 UTC = Sun Mar 31 01:59:59 1991 +06 isdst=0 /usr/share/zoneinfo/Asia/Almaty Sat Mar 30 20:00:00 1991 UTC = Sun Mar 31 02:00:00 1991 +06 isdst=1

new Date(670363200000)

Asia/{Anadyr, Aqtau} @1982 @1991 @2010

new Date(386420400000) new Date(670341600000) new Date(1269698400000)

Asia/Aqtobe, Asia/Ashgabat, Asia/Ashkhabad, Asia/Baku, Asia/Chita

...

Atlantic/Stanley @1985

new Date(495601200000)

...

Europe/Saratov

Europe/Ulyanovsk @1989 @1991

new Date(606866400000) new Date(670374000000)

Europe/Volgograd @1988 @1992

new Date(701820000000) new Date(575416800000)

Pacific/Easter @1982

new Date(384922800000)