 In a 2008 paper, cited by a POEIBE working paper, Mejía instead groups maintenance and immersion systems together as they are not in widespread use, and excludes them from their typologies; however, there are some immersion schools in use.While theoretically immersion and maintenance schools correspond to the students' first language, in practice this distinction may not be as clear in communities that are undergoing language shift.Such communities may have both children who are bilingual before school, as well as those who speak only the majority or minority language.