An action transition fires after an action state performs its action. An action transition can have a condition; the condition determines what state the system transitions into.
Line and drawing styles
When drawing action transitions, you might want to change the line drawing style from straight to straight orthogonal (Format, Symbol Format, Line). To allow greater flexibility in line drawing, you might also want to turn off griding for the diagram (Format, Diagram Format, Grid and Reduced View), and to turn off Immediate Auto Routing of lines (Tools, Preferences, Immediate Auto-Routing).
Conditions
Conditions are especially used to determine the flow after a decision. Text entered into the condition field is automatically displayed enclosed by brackets on the diagram.