Retired in ISO 639-3: Merge into Basque [eus]
Excerpt from change request document:
Souletin is just a dialect of Basque, and so is asserted by all speakers from the Soule region from the first written records in 17th century to the present. Nobody identifies his or her language as "Souletin". All their putative speakers uniformly self-identify as Basque speakers. From 1964 there is a standard Basque ("euskara batua" or unified Basque), which is the language taught in most schools, including those in the French Basque Country, and used in the media and official documents of the Basque Country.