INTERNATIONAL and NATIONAL formats are consistent with the definition in ITU-T RecommendationE.123. However we follow local conventions such as using '-' instead of whitespace asseparators. For example, the number of the Google Switzerland office will be written as"+41 44 668 1800" in INTERNATIONAL format, and as "044 668 1800" in NATIONAL format. E164format is as per INTERNATIONAL format but with no formatting applied, e.g. "+41446681800".RFC3966 is as per INTERNATIONAL format, but with all spaces and other separating symbolsreplaced with a hyphen, and with any phone number extension appended with ";ext=". It alsowill have a prefix of "tel:" added, e.g. "tel:+41-44-668-1800".Note: If you are considering storing the number in a neutral format, you are highly advised touse the PhoneNumber class.