A signal at train order offices to indicate whether train orders must be picked up.
- Red signal – train must stop or receive a clearance
- Green signal – train does not have to pick up orders
- Yellow signal – depending on the rule book, a yellow signal can mean either
Where the pick up form 19 signal is used, a red signal indicates that form 31 orders will be delivered so the crew will have to stop and sign for the orders, the orders cannot be delivered on the fly. The yellow signal indicates form 19 orders and if the orders are seen to be in position the train can pass the station without stopping, picking up the orders while in motion.
The calling on signal is used where the train order office is beyond a siding switch or other place where a train will have to stop, and the operator wants the train to advance to receive orders.