ics timezone daylight savings
BEGIN:VTIMEZONE
TZID:US Mountain Standard Time
BEGIN:STANDARD
RRULE:FREQ=YEARLY;BYMONTH=0;BYDAY=+10SU
DTSTART:16010000T000000
TZOFFSETFROM:-0700
TZOFFSETTO:-0700
END:STANDARD
END:VTIMEZONE
BEGIN:VTIMEZONE
TZID:Eastern Standard Time
BEGIN:STANDARD
RRULE:FREQ=YEARLY;BYMONTH=11;BYDAY=+11SU
DTSTART:16011101T020000
TZOFFSETFROM:-0400
TZOFFSETTO:-0500
END:STANDARD
BEGIN:DAYLIGHT
RRULE:FREQ=YEARLY;BYMONTH=3;BYDAY=+12SU
DTSTART:16010302T020000
TZOFFSETFROM:-0500
TZOFFSETTO:-0400
END:DAYLIGHT
END:VTIMEZONE