A single building that provides housing for more than one family but less than five is known as a two- to four-family property. These buildings are also sometimes called multi-dwelling units or MDUs. Ownership of this type of property is held in a single deed. Each of the dwelling units in this property must have complete independent living facilities. What constitutes independent living facilities depends on the zoning laws or ordinances of a specific place. For example, one location may require that a unit have at least 2,000 square feet, while in another community, 1,500 square feet will be adequate. For this reason, most mother-in-law quarters are either not large enough or not equipped with enough facilities to be considered a dwelling unit. Zoning laws also define the term "family." Usually the term "family" refers to a group of people who form a distinct housekeeping entity by living and cooking together.