Unusual device

Recently we (IC) were at the Dynergy/Ameren/Illinois Power plant at Baldwin, IL. to retrieve an empty BN coal train. We arrived before the plant had finished unloading the train. I climbed on the lead unit while the train was being moved to the empty track. On the conductor's desk was an item that I've never seen before; the end of a jumper cable that plugs into the MU receptacle. There was no cable attached, just the metal part. I asked the lady moving the train what it was/what it's used for. She replied that they use it to "fool" the alerter while they unload the train. Anyone out there familiar with this apparatus? I assume she meant that this device fools the lead unit by making the unit "think" that it's in an MU mode, thereby stopping the alerter from working?

Yes, it probably prevent the alerter from going off and making a penalty brake apllication. This allows the train to sit there indefinitely with the brakes released while a device at the unloading facility gradually pushes the train through and unloads the cars.