[The Conversation Africa] Sign language is on its way to become the 12th official language in South Africa after parliament recently agreed to amend the constitution to this end. The move will bring to fruition three decades of a struggle to empower the country's deaf community. An official language has legal status in a state and serves as the language of administration (conducting day-to-day state business). We asked Theo du Plessis, an emeritus professor of South African Sign Language and Deaf Studies, for his insights.