In BPMN, a data object is drawn to show data flow within a process. That is, how documents, data, and other objects are used and updated during the process. While the name data object may imply an electronic document, they can be used to represent many different types of objects, both electronic and physical.
Data objects are associated with activities and events by using a directional data association. The data association shows with an arrow, where data is produced and where it is transfered to. A diagram can be modeled without data objects, for example to reduce clutter, or with data objects to include more information without changing the basic behavior of the process.
In some cases, the data object will be shown being sent from one activity to another, i.e. the data associations connect the object with two or more activities.
A special form are data input and data output, with an arrow inside the data object shape. They are connected with one single activity, using an uni-directional data association, and simply show which data an activity receives or generates. The marker indicates whether it is an input or an output.
A collection of data may be represented by a specific multiple marker.