 Open Line working (formerly known as Red Zone) means the lines are open to train movements; this is seen as more risky than Safeguarded / Fenced / Separated areas, and is avoided in the rail industry where practicable.The COSS is responsible for the safety of the entire group and is subject to prosecution should someone be killed or injured by their negligence.To become a COSS someone should have served a suitable period of time on the railways and undertake a five-day course.