Territory string `xml:"territory,attr"`
	Type      string `xml:"type,attr"`
}

type SupplementalData struct {
	Zones []MapZone `xml:"windowsZones>mapTimezones>mapZone"`
}

func readWindowsZones() ([]*zone, error) {
	r, err := http.Get(wzURL)
	if err != nil {
		return nil, err
	}
	defer r.Body.Close()

	data, err := io.ReadAll(r.Body)
	if err != nil {
		return nil, err
	}