These are actually Northern Pacific Ry. Joint Facility Photos, I don't have the notes, but they would say "G: served by xyz RR & NP."

They have every joint track, and industry photographed and labeled.  

So you could send a message saying "page X, Item B the crossover that you pay 43.234% of costs has been repaired, here is the bill"

Neat books, I have one for the Minneapolis/St. Paul area in my collection.

-Hudson