Most important debugging facility is made available through the Boolean variables of the Switch class. In order to use this you have to have specially compiled JaCoP library where all master switches are turn on. This reduces the efficiency of the JaCoP, but gives debugging facilities. Assuming that you have turn on all master switches then you can use different switches to obtain the desired debugging information. Please, consult file JaCoP/core/Switches.java for more information.