Assignment of an ACTION (i.e., ACTION-TASK) to be time-dependent for its execution on another ACTION (e.g, ACTION-TASK or ACTION-EVENT)
Relative: e.g., starts at the end of, starts during and ends after, starts at the same time and ends after
Offset: subject ACTION is to start at some specified time interval before or after a particular reference point in the object task
Note: Absolute start and end times are specified in the attributes of ACTION-TASK