Loco Fuel load tractive effort ?

[JayPotter]

At least on CSXT, the weight assigned to a locomotive is the "nominal weight" assigned to that class of locomotive by its manufacturer. That weight is for a fully serviced locomotive. The actual weight of any given fully serviced unit might be several percentage points below or above its nominal weight. So the tonnage rating of any given unit is not a function of its fuel level. However there are some assignments in which locomotives are serviced frequently in order to maximize the amounts of tractive effort that they produce.

[BaltACD]

Unfortunately, I have no idea if fuel level is in any way considered in setting the tonnage ratings for the locomotives on my carrier.  Since way too many of them are running with less than 1000 gallons in the tank (company rules require the engineer to notify the Dispatcher when their locomotives have 1000 gallons or less), my belief is that the ratings are for locomotives that are far from full of fuel. 

[blue streak 1]

Some locos have as large as a 6000 gallon fuel tank.  At 6.7# per gallon that is a weight of ~ 40,000# weight on drivers difference. 

How are the tractive effort values figured for locos.  Full weight, half weight, empty ?  Could the difference actually mean whether a train makes it  up a grade or not ?  BALT ?