A real estate company sells houses and apartments. The company$$s listings management system stores evidence of listings. A listing contains the listing number, property address, image, year it was built, area, and price. In case of houses, people usually want to know the number of floors, size of lot, and basement characteristics. For apartments, the sizes of storage and of balcony are distinguishing characteristics. The company$$s system associates listings with agent records. These include agent ID$,$ name, address, and employment start date. A single agent manages a number of listings at a time. While a listing is usually managed by a single agent, sometimes it happens that a listing is transferred from one agent to another. It is recorded when an agent starts and ends to manage a listing.