As Jerome noted in another thread: http://www.frisco.org/shipit/index....tc-territory-was-signals-etc.4199/#post-28546 , Post #17 The Frisco’s use of train-order signals was different than the use which was described commonly in the model railroad press, i.e., when a train order signal displayed a red indication, then train must stop for “number 31” orders and sign for them, and when the order board displayed a yellow indication the train could take the orders on the fly. The 1946 and 1957 Book of Rules for the Transportation Department defines the Frisco rules 221(d) for train order signals.  Red: Stop, Yellow: Calling On, Green: Proceed. Per the Frisco Rule Book, the Red order board allowed the crew to take the orders on the fly for almost all Train Order Forms. That is, unless the crew missed the hoop. The calling-on indication applied to but one type of train order, the Form N, which was unique, because it was issued to the operator/agent and not to the Conductor and Engineer of a train.  When the operator received a Form N order, he would set the order board to yellow. At stations that used a banner-type train order board, a yellow flag or yellow lantern was used. When the train approached, the engine driver would respond to the yellow train order signal with a long-long whistle, rule 14(b), and the operator would set the order board to red. I saw a Calling-on train order signal just once at Lockwood while we were waiting for No 108 to arrive and take us to Kansas City. The events have been condensed to fit the schematics; not all tracks are shown.  Diagram 1. The Ft Scott-Springfield local is in the clear on the lumber yard track. A southbound freight, most likely No 139, is approaching slowly. The southbound A-Block is yellow, which means that No 108 is in South Greenfield. Train No 108 is about 40-45 minutes late. Per the ETT, No 108 should be superior to No 139 by class and direction.  Diagram 2. The south bound freight stopped in front of the depot. One crew member entered the depot to chat with the agent and to get the orders. The brakeman walked to the south switch of the house track, and aligned it for a move into the house track. Train No 108 appeared shortly, stopped at the red stop and proceed signal, and whistled to acknowledge the calling on signal.  Diagram 3. In response to No 108’s whistle, the agent set the order board to red, and No 108 entered the house track. The agent left the depot with two hoops, and No 108’s fireman grabbed the orders as the locomotive passed behind the depot.  Diagram 4. The agent passed the orders to No 108’s conductor as the train came to a stop behind the station to receive passengers, mail, and express. The freight train’s brakeman restored the switch to its normal positions, and No 139 resumed it southbound trip. It was an unique event, and I wish I knew more about the context that created the situation.
