if t.language != t.locale {
		loc := t.locale.Tag()
		tag, _ = tag.SetTypeForKey("rg", strings.ToLower(loc.RegionID.String())+"zzzz")
	}
	return tag
}

// IsCompact reports whether this tag is fully defined in terms of ID.
func (t *Tag) IsCompact() bool {
	return t.full == nil
}

// MayHaveVariants reports whether a tag may have variants. If it returns false
// it is guaranteed the tag does not have variants.

type Tag compact.Tag

func makeTag(t language.Tag) (tag Tag) {
	return Tag(compact.Make(t))
}

func (t *Tag) tag() language.Tag {
	return (*compact.Tag)(t).Tag()
}

func (t *Tag) isCompact() bool {
	return (*compact.Tag)(t).IsCompact()
}

// TODO: improve performance.
func (t *Tag) lang() language.Language { return t.tag().LangID }
func (t *Tag) region() language.Region { return t.tag().RegionID }