I dug out a Penn Central freight book from 1969 or so but unfortunately Penn Central had too many yards and other points
for the available letters to make any sense so for example "N" could be: Cedar Hill (old NHRR symbol), New York (west side),
NE for New England freight to and from the south via the River Line and former PRR, NS-1 - Cedar Hill - Potomac Yard, NS-3
Cedar Hill - Springfield, NY-2, 4, 6, 8, 10 and 12 were eastbound trains from Chicago, St. Louis, Indianapolis or Elkhart to
Selkirk, Dewitt or New York. There were other "N" symbols in this book for other destinations as well.
"SV" trains were generally flexi van or trail van trains on the former New York Central between various points. I did not find
an SV-40 in the book.
"V" was generally the symbol for Selkirk (I was told that this dated way back to the days before Selkirk when they had a yard
of some sort in Ravena and was originally a West Shore symbol. The book I have only shows 4 trains with a "V" symbol out
of Selkirk but in later Penn Central years there were River Line trains with VE-1 (Selkirk - Enola), VW-1 (Selkirk -Weehawken), VP-3 (Selkirk - Waverly which was the most hated train on the division by the crews), WV-2 (Weehawken -
Selkirk), EV-4 (Enola - Selkirk) and probably others as well. There was also a train VN-4 which ran from Selkirk to New York
although I never worked that train and indeed never worked the line down the West Side.
Eventually after Conrail had taken over and operated this system for a while they changed all of the designations for all of
the freight yards and terminals to a two lettered code word. When this happened Selkirk became SE, Oak Island OI, Enola
EN, Rutherford RU, Croxton CR, Oak Point OP, Elkart EL and Columbus CO. There were many more than just the ones that
I have listed here and you needed the book to figure it out.
The Conrail system was a good system and it lasted all the way until the CSX takeover after which they went to numbers
and I have no idea just how they work today.