Additionally, a sub-process can be represented in an expanded or collapsed view. An expanded view shows sub-processā details within the view of the process that it is contained in.
While a collapsed view indicates that a sub-process can be āopened upā to show a lower-level process. A collapsed-view sub-process is indicated by an additional āplusā sign positioned at the bottom center of the shape.
Beside the ācollapsed-viewā sub-process marker, BPMN specifies four types of standard markers for sub-processes, which define different behaviors of a sub-process: a loop marker, a multi-instance marker, an ad-hoc marker, and a compensation marker.
A āloop markerā defines a repeating sub-process, which means that the sub-process will start again after it reaches its end-state. A sub-process will loop as long as the set loop condition is true.
A āmultiple instanceā marker, attached to a sub-process, represents several instances of the same sub-process.
These multiple instances of the process can be performed in parallel or sequentially. Three horizontal lines represent a sequential execution whereas three vertical lines indicate that the instances should be performed in parallel.
An ad-hoc sub-process is indicated with a ātildeā symbol. This type of sub-process contains a number of embedded inner activities which are intended to be executed flexibly. The contained activities can be executed sequentially or in parallel, they can be executed multiple times in an order.
The ācompensation markerā indicates a compensation sub-process, which represents a compensation handler that is performed in case a compensation event is triggered. This happens when a transaction isnāt performed successfully.
A sub-process may have one to three of these ābehaviorā markers, in all combinations, except for loop and multi-instance which be shown at the same time.