// and unit preferences.
//
// For instance, the tag en-GB-u-rg-uszzzz specifies British English with US
// settings for currency, number formatting, etc. The CompactIndex for this tag
// will be that for en-GB, while the RegionalID will be the one corresponding to
// en-US.
func RegionalID(t Tag) (id ID, exact bool) {
	return t.locale, t.full == nil
}