You strap them on your upper arm, so that everyone knows who’s doing a particular task, and remind you of your responsibilities. The pilot man comes into use for emergency single line working, any train passing through the affected stretch has to have him with the train, rather like a single line token with arms and legs. The lookout man goes with everyone working on the track where trains are operating, he has to be placed where he can see trains coming in time to give adequate warning for the guys to get clear. PICOP is where you have possession of a stretch of track for engineering work, but you can still get trains wanting to pass through, such as a ballast train, say, and he has to give permission for the train to pass through that stretch, and make sure everybody is clear, also sign for the start and finish of possession. Engineering Supervisor is similar without the possession, mainly worrying about stuff like lookouts. TSC is something stitched on since I retired.