An Caighdeán Oifigiúil
An Caighdeán Oifigiúil ([ənˠ ˌkəidʲaːn̪ˠ ˈɛfʲɪɟuːlʲ], "The Official Standard"), often shortened to An Caighdeán, is a written variety of the Irish language that is used as the standard or state norm for the spelling and the grammar of the language. It is used in official publications, and is the form taught in most schools in the Republic of Ireland.