a. the person giving the signals, hereinafter called the signaller, uses arm and hand movements to give manoeuvring instructions to the person receiving the signals, hereinafter called the operator; b. the signaller can monitor all manoeuvres with his/her eyes without thereby putting him/herself at risk; c. if the conditions described in b) above cannot be met, one or more additional signallers are deployed; d. the signaller's tasks consist exclusively of giving instructions in connection with the manoeuvring, and of attending to the safety of employees in the vicinity; e. the operator interrupts the manoeuvre being carried out and asks for new instructions if it proves impossible to carry out the order with the necessary degree of safety.
