ATSF engine service designation

Santa Fe roster designation fleet
This is an elaboration of what I based on 's ideas. I hope you like it.

Primary long distance engines- Passenger locomotives that run at speeds of up to 125 mph, and make limited stops between destinations
BR class 221 units

Secondary long distance engines- Passenger locomotives that use same routes as long distance trains, but go slower and stop more often.
3450, 3460 4-6-4s
3400, 3600 4-6-2s
EMD F59PHI
2900, 3751, 3765, 3776 series 4-8-4s
6-4-4-4 cab forward

Dual service engines- Locomotives  that are able to be used on both freight and passenger trains.
EMD FT
EMD GP units
3700 4-8-2s
EMD E- units

Fast freight engines-Locomotives designated to haul fast freights like merchandise or the Tropicana juice train.
EMD SD units
EMD GP units
C44-9W
B40-8/W
C40-8W
4101, 4193 2-8-4s
900, 1600, 1674, 3800 2-10-2s
3160, 4000 2-8-2s
1798 class 2-6-6-4s (former N&W)

Slow freight engines- Locomotives designated to operate longer, heavier freight trains.
GE Dash 9s
GE Dash 8s
GE CWs
5000, 5001, 5011 2-10-4s

Branch line passenger trains- Locomotives designated to operate passenger trains on branch lines or locals.
EMD Budd cars

Branch line/ local steam engines- Locomotives designated to run local or branch line trains.
2507, 2535 2-8-0s
1000, 1050 2-6-2s
3500 4-6-2s

Switchers- Locomotives designated to switch cars in RR yards.
2110 0-6-0s
2535 0-8-0s
tank engines
EMD SW locomotives