The reporting mark and number of a box car was usually stenciled on the inside wall, about 6' up to the left of the door opening on both sides.
This was important in terminals where a car's road and number might not be readily visible on the outside.
Especially so, in places where box cars were lined up side by side with their doors open on both sides with ramps put across to the next car, so all could be loaded at the same time regardless of which track they were on.
It was important to have a car's ID plainly positioned so it could be identified by crews loading the cars based on the information and destination for the items being loaded.
Each car's waybill also carried information as to what had been loaded into it.
Important to know for accurate delivery, also settlement in the event of any damage or losses to loads along the way.