In our series of letters from African journalists, Mannir Dan Ali, former editor-in-chief of the Daily Trust newspaper, looks at what a row over Arabic script reveals about Nigeria's divides. A lawyer has asked a court in Nigeria's commercial city of Lagos to compel the country's central bank to remove the Arabic script which appears on most naira banknotes. The lettering states the note's currency value. He also wants the army to stop using the Arabic inscription: "Victory is from God", on its logo. The move is likely to reopen an old controversy over the use of Arabic script, which some see as an attempt to Islamise the country. But many seem unaware that the Arabic script used to write in several African languages is known as "Ajami". It was the first means of literacy on the continent, centuries before Western colonisers and Christian missionaries arrived with their Roman script and its A-Z alphabet. Among others, Swahili in East Africa, Tamashek, the language of the Tuaregs in North and West Africa, and Nigerian languages like Kanuri, Nupe, Yoruba, Fulfulde and Hausa all use Ajami. Scholars and administrators in the Sokoto Caliphate, which dominated much of present-day northern Nigeria in the 19th Century, used Ajami to write many documents and books. Nana Asma'u, the daughter of Sheikh Usman Dan Fodio, who founded the caliphate, was a renowned and prolific poet - and probably the first woman to write several books in Hausa and Fulfulde using Ajami. More than 150 years after her death, it is Ajami Hausa, not Arabic, that is on the naira notes.