Architecting and designing : Business Process Analysis (BPA) : BPMN : Checking connections on business process diagrams
  
Checking connections on business process diagrams
Use the Check Connections option to enforce Business Process diagram rules. For example, when selected, the option prevents a process connected to a message flow from being moved into the same lane from which the flow originated. It also prevents a Timer Event symbol from being connected to a Message Flows symbol.
1 Right-click a Business Process diagram, and then click Diagram Properties.
2 In the Introduction tab (page ‘1 of 2), select Check Connections.
3 Click Apply and OK to close the dialog.
See also
BPMN