2. He gives us some idea how he might achieve those rezonings by calling for repeal of a state law that limits residential buildings to a “floor area ratio” of 12. That law means you can’t have more than 12 square feet of residential building area per square foot of land area. Mr. de Blasio would instead have the city set its own such limits through the zoning process. Currently, the city allows a ratio of up to 18 for office buildings in the densest parts of Manhattan. Mr. de Blasio hasn’t proposed a specific limit for residences, but if the city copied its practice for office buildings, it could allow up to 50 percent more residential development on high-density sites — which would give the city something very valuable to offer developers in exchange for building affordable housing.

3. He proposes to use tax policy to discourage property owners from keeping their land vacant or their buildings underoccupied.

4. He calls for a relaxation of minimum parking requirements for affordable housing development in certain areas of the city, noting: “Where parking is built for affordable housing, spaces often go unused. The construction of unnecessary parking spots increases construction costs and may deter development or reduce the number of affordable units that can be produced.”

5. He’d change setback requirements (rules about how far away from the street a building wall must be to reach a given height) in order to increase the effective amount of building area that is allowed on a given site. Over the last few decades, developers have shifted toward taller ceiling heights, which has meant that the existing setback rules effectively allow for less floor space than they used to.