Develop a Brief Use Case Description. Make assumptions where necessary. The real estate business relies on an extensive amount of information used in the buying and selling of real property. Most communities of real estate agents and brokers have formed cooperative organizations to help consolidate and distribute information on the real estate profession, real estate trends, properties in the community, historical records of property sales, and current listings of properties for sale. These organizations are usually referred to as the Community Board of Realtors. One of the functions of the Board of Realtors is to provide a Multiple Listing Service (MLS) system that supplies information that local real estate agents use to help them sell houses to their customers. Agents list houses for sale (listings) by contracting with homeowners. The agent works for a real estate office, which sends information on the listing to the MLS. Therefore, any agent in the community can get information on the listing. The MLS systems include lots of information on a listing. It is now common to include dozens of photos, video tours, Google map information, prior sales, and so forth. For now, lets keep it simple and assume a listing includes the address, year built, square feet, number of bedrooms, number of bathrooms, owner name, owner phone number, asking price, and status code. An agent will directly request information from the MLS system on listings that match customer requirements. Information is provided on the house, on the agent who listed the house, and on the real estate office for which the agent works. This information is needed because an agent might want to call the listing agent to ask additional questions or call the homeowner directly to make an appointment to show the house. Although it seems dated, once each week, the MLS produces a listing booklet that contains information on all listings. These booklets are sent to some real estate agents because many think they are easier to flip through and write on. Sometimes, agents and owners decide to change information about a listing, such as reducing the price, correcting previous information on the house, or indicating that the house is sold. The agent updates the information directly on the MLS system.