@types in vue.i18n

Hello,

I'm using vue-i18n on my nuxt app with typescript.

I have a simple question : Why in

declare module 'vue/types/options' {
	interface ComponentOptions<V extends Vue> {
		i18n?: {
			messages?: VueI18n.LocaleMessages
			dateTimeFormats?: VueI18n.DateTimeFormats
			numberFormats?: VueI18n.NumberFormats
			sharedMessages?: VueI18n.LocaleMessages
		}
	}
}

locale and fallbackLocaledoes not appear in this structure ? I try to use them but typescript obviously pull an error.

Thank you Maxime