You have me there. I should have said, "if it wasn't important for the number of cars in a series to be accurate, why was it tracked in the ORER?" My response was in reply to George Eichelberger's post of April 8, 2017. Apparently the Southern didn't care too much about the accuracy of the listings of cars being taken out of service. The GN did, dutifully counting down the numbers of GN truss rod cars, despite their wholesale retirement in the postwar years.