Understanding railroad markings. Pretty much every piece of rolling stock, whether freight or passenger, or the motive power (locomotives) have their own unique identifying number. Railroads can use two, three or four letters and up to six numbers. Such as this CN grain car, CN 100942.
This particular car is stenciled "Government Of Canada", because it was originally part of a government fleet designed to ensure sufficient grain car availability to get the product to market. That fleet was ended and the rolling stock was taken over by CN (and CP, who had similar cars on their lines).
If you see a car initial ending in 'X', it means that the car is not owned by a particular railroad, but rather a non rail company owns it. For example, you'll know this Exxon tanker XOMX 110302 isn't owned by a railroad due to the last X. A great many private and company owned rail cars have this X, just because someone doesn't own a railroad doesn't mean that they can't have a fleet of rail cars.
You can see on the previous grain car photo that there is brown paint just after the CN markings, when the car was government owned it had the markings CNWX, and after being taken over by CN it was altered.
One of the largest pools of lease cars is run by the TTX Company, usually painted their signature yellow. They keep a large pool of flatcars, container cars, boxcars and auto racks in service. Many class one railroads use these in quantity, because for business purposes it means that they're not carrying the depreciation or repair and maintenance costs, instead paying for the use on a trip basis, so you'll commonly see TTX cars on every major rail line in the continent. So if you've ever wondered what that TTX railroad was, and why you don't see TTX locomotives, that's the reason - it isn't a real railroad. By the way, TTX originally stood for Trailer Train.