Activity diagram

[1] Activity diagrams are constructed from a limited number of shapes, connected with arrows.

[4] The most important shape types are as follows: Arrows run from the start towards the end and represent the order in which activities happen.

[5] However, the join and split symbols in activity diagrams only resolve this for simple cases.

The meaning of the model is not clear when these symbols are arbitrarily combined with decisions or loops.

[citation needed] UML activity diagrams in version 2.x can be used in various domains, e.g. in design of embedded systems.