The subject railroad indicated that it often uses the following four groups when conducting studies of employee morale: (1) shop craft unions - International Association of Machinists (IAM), International Brotherhood of Boilermakers and Blacksmiths (IBBB), International Brotherhood of Electrical Workers (IBEW), International Brotherhood of Firemen and Oilers (
IBFO), Sheetmetal Workers International Association (SWIA), and Carmen Division of the Transportation Communication Union (TCU); (2) train crews - Brotherhood of Locomotive Engineers (BLE) and United Transportation Union (UTU); (3) clerks - TCU (except for Carmen); and (4) maintenance - Brotherhood of Maintenance of Way Employees (BMWE) and Brotherhood of Railway Signalmen (BRS).