Vatican City - Latin America's first pope - Jorge Mario Bergoglio - will be known as Francis, rather than Francis I, until such time as a future pope chooses the same name.
"Cardinalem Bergoglio qui sibi nomen imposuit Franciscum," the Vatican's proto-deacon said as he presented the new leader of the world's 1.2 billion Catholics to the world on Wednesday - crucially without adding the world "Primum" (the first).
He will remain a plain Francis until a successor calls himself Francis II - if any should choose to do so - at which point he will go down in history as Francis I.
The first pope to add "the first" to his name was Cardinal Albino Luciani, who took the name John Paul I in 1978.
Papal names down the centuries are inextricably linked to the legacies of the men who have ruled the Church.
Bergoglio's decision to become the first pope ever to go by the name Francis is seen as highly significant.
The moniker draws on the legacy of St Francis of Assisi, the 13th-century founder of the Franciscan Order and a symbol of asceticism.
Some of the quirkier papal names from history have proved unpopular. Among those that have never been used more than once are Simplicius and Hilarius.