Data objects may be text files, drawings and spreadsheets. These are said to be of different "types". The object type can be set by the user and is used in a variety of operations such as sorting and assigning associations. Data objects are associated with an "object handler"; this is a generic term for a program that is used with the object.
When the user double clicks the mouse on the icon, the contents of the object are displayed by the object handler in a window. When the window is closed, the object handler saves its data and the location and state of the window for the next time it is opened.
When an object is dragged to a container it is moved there. When it is dragged to a device, the default action depends on the device; the contents are copied to a printer or diskette, but moved to a shredder. When an object is dragged to another data object, the result depends upon whether the target object knows what to do with the object being dragged. To achieve this, there must be a communications protocol by which the objects may communicate with one another, and an agreement on which commands are understood. These considerations are discussed in Presentation Manager and Workplace Shell Application Development.