According to official sources, on November 16, 2019, MakerDAO launched a proposal through multi-mortgage Dai – multi-mortgage Dai will be officially launched at 12 pm on Monday, November 18th, Beijing time. At the same time, the MakerDAO development team released a multi-collateral Dai main network contract. The release of the main network contract represents that the multi-mortgage Dai has been prepared from the system, and the current debt limit of Dai is set to zero. At 12 o'clock on the evening of November 18, the debt ceiling will be activated to 153 million Dai (100 million for Sai upgrade reserve, 50 million for multi-mortgage Dai ETH debt ceiling, 3 million for BAT debt Upper limit). At that time, it will mean that the multi-mortgage Dai system will be officially launched, and users can mortgage Dai and upgrade the single mortgage Sai to Dai.