An interface that uses a primary window to contain related document windows. The parent window's title bar is displayed along with the child window's title bar. If the child window displays a document window, an icon that indicates the application data's file type appears in the child window's title bar.

An application that can support multiple documents from one application instance. MDI object applications can simultaneously service a user and one or more embedding containers. . The standard user-interface architecture for Windows-based applications. A multiple document interface application enables the user to work with more than one document at the same time. Each document is displayed within the client area of the application's main window. See also child window, client area, single document interface (SDI). .

A Windows interface style in which all of an applications' windows are housed in a large window known as the parent window. Compare with single document interface.