VC       Vents Closed to Destination
VO       Vents Open to Destination
VS       Standard Ventilation at 32 Degrees
V40      Standard Ventilation at "--" Degrees (Other than 32 Degrees)
VOI      Vents on Irons
VD40     Diagonal Ventilation at "--" Degrees (Other than 32 Degrees) - Open Vent Each 
         End of Car
VDOI     Diagonal Vents on Irons
VS10     Standard Ventilation - Substitute Carrier's Protective Service at First 
         Terminal Train Yard where Heaters Are Available and Outside Temperature is 10 
         Degrees Above Zero or Lower (PPT #619 Rules 385 and 515)