Examiners love this area as nine times out of ten it is so black and white. You must choose the correct lane for the manoeuvre you are trying to attempt. So, for example, if you go straight ahead from a lane marked for turning left you have blown it, likewise indicating right while in a straight ahead lane will also ruin the test. Clearly the most obvious area where this will occur is at roundabouts. Generally if you pick the wrong lane it is a serious fault. However, this box can also be used to mark your behaviour on dual carriageways. You must keep to the left unless you are overtaking; once you have overtaken a vehicle you must move back into the left lane. The examiner will expect you to overtake slower vehicles where conditions allow. If you have done nothing else wrong the examiner might let it go with a rider fault, but normally as with other areas of lane discipline, they tend to mark this as a serious fault.