Vatican City, February 12 - Vatican Spokesman Federico Lombardi said Tuesday a new title may have to be coined to refer to Pope Benedict XVI once he officially steps down. "Perhaps Bishop Emeritus of Rome," he said. Benedict, who surprised the world with his plan to step down on Monday, will retain his rank as bishop after his resignation becomes official on February 28, and will eventually move into a monastery inside the Vatican walls. In order to remain a cardinal, he would have to be reappointed, something Lombardi seemed to rule out Tuesday. "It will be interesting to see how we address him, how he will be called," said Lombardi. "It will be difficult to call him cardinal".