Here are some common terms that are placed in chat or heard over the scanner.

 TermDefinition 
 COFC Container on Flat Car
 CSAOConrail Shared Assets Operations 
 End of Train Device (EOT)The end of train device is hooked into the brake system. It can be managed by the engineer, where the FRED can not. 
Flange SquealSqueal is presumably caused by the lateral sticking and slipping of wheels across top of the railroad track. It results in vibrations in the wheel that increase until a stable amplitude is reached.
 Flashing Rear End Device (FRED) A FRED is a blinking red light run off a battery that is in an EOT device. If you hear a whirling noise, it's the turbine driven generator that keeps the battery charged. The turbine is driven through the air being passed through the train line hose. 
 JBSJuniata Back Shops 
 Key Train A "key train" is any train as described as:
1. One or more loaded tank cars containing materials that require the phrase "Poison-Inhalation Hazard" or "Inhalation Hazard" on the shipping papers OR
2. 20 or more carloads or intermodal portable tanks of hazardous materials OR
3. one or more loads of Spent Nuclear Fuel (SNF) on high level radioactive waste
 NEC North East Corridor
 OLSOperation Lifesaver 
 "OSS"Operations & Service Support - oversees industry switching current demurrage records, crew work orders, and car movement reporting.
 Road PowerHead end of an engine 
 Sailboat FuelEmpty intermodal flat cars (delivering "wind") 
 SIPSignal Interruption Point 
 TOFC Trailer on Flat Car
 TOL (Track Occupancy Light) Issue Dispatcher display is showing something in a block that's not actually there. Usually happens when it's rainy or there is a bad isolator somewhere.
 T&EStands for "Train and Engine". Normally heard when the dispatcher is giving a Track Authority.  
 "Van"Intermodal Train