The Indian cabinet has approved funds for a census and a population survey to be held next year despite weeks of protests over a citizenship law that critics say is anti-Muslim. Authorities say the updated National Population Register (NPR) will be a comprehensive list of all residents. However, critics say it will be a list from which "doubtful citizens" will be asked to prove they are Indian. More than 20 people have died in protests over the citizenship law. What is the NPR?