Baldauf (2005) proposed a framework for language policy with four types of activities: status planning, corpus planning, language in education planning, and prestige planning. Status planning determines the political status and functions assigned to a language, such as official language. Corpus planning involves efforts to codify and elaborate a language. Language in education planning sets policies around what languages are used in education. Prestige planning aims to change perceptions of the social status of a language. Language shift can be planned through government policies or unplanned through voluntary community changes in language attitudes and use. Education typically plays a strong role in both planned and unplanned language shift.