Create a Level 0 DFD (NOT a Context DFD) for the following system.

Real Estate Service Management System (RESMS) supplies information that local real estate agents use to help them to sell houses and lands to their customers.

During the month, agents list houses and lands for sale by contracting with owners. The system takes the listing information and adds it to the existing list of real estate items.

The agent works for a real estate office whose staff sends information on the listing to the multiple listing services. Therefore, any agent in the community can get information on the listing. Information on a listing includes the address, year built, square feet, number of bedrooms, owner name, owner phone number, asking price and status code.

At any time during the month an agent requests information on listings that match customer requirements, so the agent contacts the multiple listing services with the request. Information on the house and on the agent who listed the house and the lands is provided.

Twice each month, the multiple listing service system produces a listing book that contains information on all listings. These books are sent to all of the real estate agents. Many real estate agents want the books (which are easier to flip through), so they are provided even though the information is often out of date.

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.