timezones

type Change struct {
	// Start is time when the previous zone changes to ZoneIndex.
	Start time.Time

	// ZoneIndex which takes effect since Start.
	// Must be in range 0 to len(Zones)-1.
	ZoneIndex int
}

type Template struct {
	// Name of the new location.
	Name string

	// Zones lists local zones.
	// At the beginning of time, Zone at index 0 applies.
	// When that zone changes to another zone is specified in Changes.
	// Maximum of 254 zones can be present.
	Zones []Zone

	// Changes specifies zone transitions.
	// Changes Start times must be in strictly increasing order.
	// If Extend is non-empty, the ZoneIndex of the last Change is ignored, Extend is used instead.
	// Changes might be empty, in that case Extend must be non-empty.
	Changes []Change

	// If Extend is non-empty, it replaces the definition of zones since the last change.
	// If there is at most one zone specified by Zones and Changes, Extend applies since the beginning of time.
	// Extend is a TZ string conforming to RFC 8536, section 3.3.
	Extend string
}

type Zone struct {
	// Name of the zone.
	Name string

	// Offset to add to UTC time to get local time.
	// Zones with positive offsets are east of UTC.
	Offset time.Duration

	// IsDST reports whether Daylight Savings Time is in effect.
	IsDST bool
}