Category and index letters for freight cars (excluding articulated and multiple wagons) as of January 1st, 2015:

Index letters with an international value common to all categories:
- q: pipe for electric heating which can be supplied by all accepted currents;
- qq: pipe and installation for electric heating which can be supplied by all accepted currents;
- s: wagons authorised to run under "s" conditions (max. speed 100 km/h);
- ss: wagons authorised to run under "ss" conditions (max. speed 120 km/h).

Index letters with a national value:
t, u, v, w, x, y, z

E: open high-sided wagon (reference wagon: of ordinary type, with side and end tipping, with flat floor, with 2 axles inside length of the wagons over or equal to 7,70 m and the highest load limit between 25 t and 30 t, with 4 axles inside length of the wagons over or equal to 12 m and the highest load limit between 50 t and 60 t, with 6 axles or more inside length of the wagons over or equal to 12 m and the highest load limit between 60 t and 75 t):
- a: with 4 axles;
- aa: with 6 axles or more;
- c: with floor traps (this concept only applies to open high-sided wagons with a flat floor, and provided with a device enabling them to be used, either as ordinary wagons with a flat bottom, or for gravity unloading of certain goods by suitable positioning of the traps);
- k: with 2 axles highest load limit under 20 t, with 4 axles highest load limit under 40 t, with 6 axles or more highest load limit under 50 t;
- kk: with 2 axles highest load limit between 20 t and 25 t, with 4 axles highest load limit between 40 t and 50 t, with 6 axles or more highest load limit between 50 t and 60 t;
- l: without side tipping;
- ll: without floor traps (only applicable to 1520 mm gauge wagons);
- m: with 2 axles inside length of the wagons under 7,70 m, with 4 axles or more inside length of the wagons under 12 m;
- mm: with 4 axles or more inside length of the wagons over 12 m (only applicable to 1520 mm gauge wagons);
- n: with 2 axles highest load limit over 30 t, with 4 axles highest load limit over 60 t, with 6 axles or more highest load limit over 75 t;
- o: without end tipping;
- p: with station for brakeman (only applicable to 1520 mm gauge wagons).

F: open high-sided wagon (reference wagon: of special type, with 2 axles highest load limit between 25 t and 30 t, with 3 axles highest load limit between 25 t and 40 t, with 4 axles highest load limit between 50 t and 60 t, with 6 axles or more highest load limit between 60 t and 75 t):
- a: with 4 axles;
- aa: with 6 axles or more;
- b: high capacity with axles (volume over 45m³);
- c: with controlled gravity unloading, on both sides, alternately, at the top (without a flat floor and have no tipping facility either at the end or the side);
- cc: with controlled gravity unloading, on both sides, alternately, at the bottom (without a flat floor and have no tipping facility either at the end or the side);
- f: suitable for traffic with Great Britain;
- ff: suitable for traffic with Great Britain (by tunnel exclusively);
- fff: suitable for traffic with Great Britain (by train-ferry exclusively);
- k: with 2 axles highest load limit under 20 t, with 4 axles highest load limit under 40 t, with 6 axles or more highest load limit under 50 t;
- kk: with 2 axles highest load limit between 20 t and 25 t, with 4 axles highest load limit between 40 t and 50 t, with 6 axles or more highest load limit between 50 t and 60 t;
- l: with bulk gravity unloading, on both sides, simultaneously, at the top (without a flat floor and have no tipping facility either at the end or the side);
- ll: with bulk gravity unloading, on both sides, simultaneously, at the bottom (without a flat floor and have no tipping facility either at the end or the side);
- n: with 2 axles highest load limit over 30 t, with 3 axles highest load limit over 40 t, with 4 axles highest load limit over 60 t, with 6 axles or more highest load limit over 75 t;
- o: with axial bulk gravity unloading, at the top (without a flat floor and have no tipping facility either at the end or the side);
- oo: with axial bulk gravity unloading, at the bottom (without a flat floor and have no tipping facility either at the end or the side);
- p: with axial controlled gravity unloading, at the top (without a flat floor and have no tipping facility either at the end or the side);
- pp: with axial controlled gravity unloading, at the bottom (without a flat floor and have no tipping facility either at the end or the side);
- ppp: with station for brakeman (only applicable to 1520 mm gauge wagons).

G: covered wagon (reference wagon: of ordinary type, with at least 8 ventilation apertures, with 2 axles inside length of the wagons between 9 m and 12m and the highest load limit between 25 t and 30 t, with 4 axles inside length of the wagons between 15 m and 18 m and the highest load limit between 50 t and 60 t, with 6 axles or more inside length of the wagons between 15 m and 18 m and the highest load limit between 60 t and 75 t):
- a: with 4 axles;
- aa: with 6 axles or more;
- b: high capacity (with 2 axles inside length of the wagon over 12 m and payload capacity over 70 m³, with 4 axles or more inside length of the wagon over 18 m);
- bb: with 4 axles or more inside length of the wagon over 18 m (only applicable to 1520 mm gauge wagons);
- g: for grain;
- h: for fruits and vegetables (applies only to wagons provided with additional ventilation apertures at the floor level);
- k: with 2 axles highest load limit under 20 t, with 4 axles highest load limit under 40 t, with 6 axles or more highest load limit under 50 t;
- kk: with 2 axles highest load limit between 20 t and 25 t, with 4 axles highest load limit between 40 t and 50 t, with 6 axles or more highest load limit between 50 t and 60 t;
- l: with less than 8 ventilation apertures;
- ll: with enlarged doors apertures (only applicable to 1520 mm gauge wagons);
- m: with 2 axles inside length of the wagons under 9 m, with 4 axles or more inside length of the wagons under 15 m;
- n: with 2 axles highest load limit over 30 t, with 4 axles highest load limit over 60 t, with 6 axles or more highest load limit over 75 t;
- o: with 2 axles inside length of the wagons under 12 m and payload capacity over 70 m³;
- p: with station for brakeman (only applicable to 1520 mm gauge wagons).

H: covered wagon (reference wagon: of special type, with 2 axles inside length of the wagons between 9 m and 12m and the highest load limit between 25 t and 30 t, with 4 axles inside length of the wagons between 15 m and 18 m and the highest load limit between 50 t and 60 t, with 6 axles or more inside length of the wagons between 15 m and 18 m and the highest load limit between 60 t and 75 t):
- a: with 4 axles;
- aa: with 6 axles or more;
- b: high capacity (with 2 axles inside length of the wagon between 12 m and 14 m and payload capacity over 70 m³ *, with 4 axles or more inside length of the wagon between 18 m and 22 m);
- bb: very high capacity (with 2 axles or more inside length of the wagon over 14 m, with 4 axles or more inside length of the wagon over 22 m);
- c: with end doors;
- cc: with end doors and fitted internally for the transport of motor cars;
- d: with floor traps;
- dd: with tipping body (only applicable to 1520 mm gauge wagons);
- e: with 2 floors;
- ee: with 3 floors or more;
- f: suitable for traffic with Great Britain*;
- ff: suitable for traffic with Great Britain (by tunnel exclusively);
- fff: suitable for traffic with Great Britain (by train-ferry exclusively)*;
- g: for grain;
- gg: for cement;
- h: for fruits and vegetables (applies only to wagons provided with additional ventilation apertures at the floor level);
- hh: for mineral fertiliser (only applicable to 1520 mm gauge wagons);
- i: with opening or shunt walls;
- ii: with very robust opening or shunt walls (only applicable to 1435 mm gauge wagons);
- k: with 2 axles highest load limit under 20 t, with 4 axles highest load limit under 40 t, with 6 axles or more highest load limit under 50 t;
- kk: with 2 axles highest load limit between 20 t and 25 t, with 4 axles highest load limit between 40 t and 50 t, with 6 axles or more highest load limit between 50 t and 60 t;
- l: with movable partitions (movable partitions may be dismounted temporarily);
- ll: with lockable movable partitions (movable partitions may be dismounted temporarily);
- m: with 2 axles inside length of the wagons under 9 m, with 4 axles or more inside length of the wagons under 15 m;
- mm: with 4 axles or more inside length of the wagons over 18 m;
- n: with 2 axles highest load limit over 28 t, with 4 axles highest load limit over 60 t, with 6 axles or more highest load limit over 75 t;
- o: with 2 axles inside length of the wagons between 12 m and 14 m and payload capacity over 70 m³;
- p: with station for brakeman (only applicable to 1520 mm gauge wagons).
* 2 axles wagons bearing the index letters "f", "fff" can have a payload capacity less than 70 m³

I: temperature-controlled wagon (reference wagon: refrigerator wagon, with class IN thermal insulation, with motor-driven ventilation, with gratings and ice bunker over 3,5 m³, with 2 axles floor area between 19 m² and 22 m² and the highest load limit between 15 t and 25 t, with 4 axles floor area over 39 m² and the highest load limit between 30 t and 40 t):
- a: with 4 axles;
- b: with 2 axles and large floor area between 22 m² and 27 m²;
- bb: with 2 axles and very large floor area over 27 m²;
- c: with meat hooks;
- d: for fish;
- e: with electric ventilation;
- f: suitable for traffic with Great Britain;
- ff: suitable for traffic with Great Britain (by tunnel exclusively);
- fff: suitable for traffic with Great Britain (by train-ferry exclusively);
- g: with mechanical refrigeration;
- gg: refrigerator with liquefied gas;
- h: with class IR thermal insulation;
- i: mechanically refrigerated by the machinery of an accompanying technical wagon;
- ii: accompanying technical wagon;
- k: with 2 axles highest load limit under 15 t, with 4 axles highest load limit under 30 t;
- l: insulated without ice bunkers;
- m: with 2 axles floor area under 19 m², with 4 axles floor area under 39 m²;
- mm: with 4 axles floor area over 39 m² (only applicable to 1520 mm gauge wagons);
- n: with 2 axles highest load limit over 25 t, with 4 axles highest load limit over 40 t;
- o: with ice bunkers of capacity less than 3,5 m³;
- p: without gratings.

K: 2 axles flat wagon (reference wagon: of ordinary type, with drop sides and short stanchions, inside length of the wagons over 12m and the highest load limit between 25 t and 30 t):
- b: with long stanchions;
- g: fitted for the transport of containers;
- i: with removable cover and non-removable ends;
- j: with shock-absorbing device;
- k: highest load limit under 20 t;
- kk: highest load limit between 20 t and 25 t;
- l: without stanchions;
- m: inside length of the wagon between 9 m and 12 m;
- mm: inside length of the wagon under 9 m;
- n: highest load limit over 30 t;
- o: with non-removable sides;
- p: without sides;
- pp: with removable sides.

L: 2 axles flat wagon (reference wagon: of special type, inside length of the wagons over 12m and the highest load limit between 25 t and 30 t):
- b: with special fittings for securing purposes for medium-sized containers;
- c: with swivelling bolster;
- d: fitted out for the transport of motor cars, without deck;
- e: with decks for the transport of motor cars;
- f: suitable for traffic with Great Britain;
- ff: suitable for traffic with Great Britain (by tunnel exclusively);
- fff: suitable for traffic with Great Britain (by train-ferry exclusively);
- g: fitted for the transport of containers (wagons used solely for the transport of containers);
- h: fitted out for the transport of steel coils, eye to side (wagons used solely for the transport of steel coils);
- hh: fitted out for the transport of steel coils, eye to sky (wagons used solely for the transport of steel coils);
- i: with removable cover and non-removable ends;
- ii: with very robust removable metallic cover (only applicable to 1435 mm gauge wagons) and non-removable ends;
- j: with shock-absorbing device;
- k: highest load limit under 20 t;
- kk: highest load limit between 20 t and 25 t;
- l: without stanchions;
- m: inside length of the wagon between 9 m and 12 m;
- mm: inside length of the wagon under 9 m;
- n: highest load limit over 30 t;
- p: without sides.

O: mixed flat and open high-sided wagon (reference wagon: of ordinary type, with 2 or 3 axles, with drop sides or ends and stanchions, with 2 axles inside length of the wagon over 12 m and the highest load limit between 25 t and 30 t, with 3 axles inside length of the wagon over 12 m and the highest load limit between 25 t and 40 t):
- a: with 3 axles;
- f: suitable for traffic with Great Britain;
- ff: suitable for traffic with Great Britain (by tunnel exclusively);
- fff: suitable for traffic with Great Britain (by train-ferry exclusively);
- k: highest load limit under 20 t;
- kk: highest load limit between 20 t and 25 t;
- l: without stanchions;
- m: inside length of the wagon between 9 m and 12 m;
- mm: inside length of the wagon under 9 m;
- n: with 2 axles the highest load limit over 30 t, with 3 axles highest load limit over 40 t.

R: flat bogies wagon (reference wagon: of ordinary type, with drop ends and stanchions, inside length of the wagons between 18 m and 22 m and the highest load limit between 50 t and 60 t):
- b: inside length of the wagon over 12 m;
- e: with drop sides;
- g: fitted for the transport of containers;
- h fitted out for the transport of steel coils, eye to side;
- hh fitted out for the transport of steel coils, eye to sky;
- i: with removable cover and non-removable ends;
- j: with shock-absorbing device;
- k: highest load limit under 40 t;
- kk: highest load limit between 40 t and 50 t;
- l: without stanchions;
- m: inside length of the wagon between 15 m and 18 m;
- mm: inside length of the wagon under 15 m;
- n: highest load limit over 60 t;
- o: with non-removable ends less than 2 m in height;
- oo: with non-removable ends, 2 m or more in height;
- p: without drop ends;
- pp: with removable sides.

S: flat bogies wagon (reference wagon: of special type, with 4 axles inside length of the wagons over 18 m and the highest load limit between 50 t and 60 t, with 6 axles or more inside length of the wagons over 22 m and the highest load limit between 60 t and 75 t):
- a: with 6 axles - 2 bogies of 3 axles;
- aa: with 8 axles or more;
- aaa: with 4 axles - 2 bogies of 2 axles (only applicable to 1520 mm gauge wagons);
- b: with special fittings for securing purposes for medium-sized containers;
- c: with swivelling bolster;
- d: fitted out for the transport of motor cars, without deck;
- e: with decks for the transport of motor cars;
- f: suitable for traffic with Great Britain;
- ff: suitable for traffic with Great Britain (by tunnel exclusively);
- fff: suitable for traffic with Great Britain (by train-ferry exclusively);
- g: fitted for the transport of containers, total loading length up to 60 feet;
- gg: fitted for the transport of containers, total loading length over 60 feet;
- h fitted out for the transport of steel coils, eye to side;
- hh fitted out for the transport of steel coils, eye to sky;
- i: with removable cover and non-removable ends;
- ii: with very robust removable metallic cover (only applicable to 1435 mm gauge wagons) and non-removable ends;
- j: with shock-absorbing device;
- k: with 4 axles highest load limit under 40 t, with 6 axles or more highest load limit under 50 t;
- kk: with 4 axles highest load limit between 40 t and 50 t, with 6 axles or more highest load limit between 50 t and 60 t;
- l: without stanchions;
- m: with 4 axles inside length of the wagon between 15 m and 18 m, with 6 axles or more inside length of the wagon between 18 m and 22 m;
- mm: with 4 axles inside length of the wagon under 15 m, with 6 axles or more inside length of the wagon under 18 m;
- mmm: with 4 axles inside length of the wagon over 22 m;
- n: with 4 axles highest load limit over 60 t, with 6 axles or more highest load limit over 75 t;
- p: without sides.

T: wagon with opening roof (reference wagon: with 2 axles inside length of the wagons between 9 m and 12 m and the highest load limit between 25 t and 30 t, with 4 axles inside length of the wagons between 15 m and 18 m and the highest load limit between 50 t and 60 t, with 6 axles or more inside length of the wagons between 15 m and 18 m and the highest load limit between 60 t and 75 t):
- a: with 4 axles;
- aa: with 6 axles or more;
- b: high capacity (with 2 axles inside length of the wagons over 12 m, with 4 axles or more inside length of the wagons over 18 m);
- c: with end doors;
- d: with controlled gravity unloading, on both sides, alternately, at the top;
- dd: with controlled gravity unloading, on both sides, alternately, at the bottom;
- e: with unobstructed height of the doors over 1,90 m;
- f: suitable for traffic with Great Britain;
- ff: suitable for traffic with Great Britain (by tunnel exclusively);
- fff: suitable for traffic with Great Britain (by train-ferry exclusively);
- g: for grain;
- h fitted out for the transport of steel coils, eye to side;
- hh fitted out for the transport of steel coils, eye to sky;
- i: with opening walls;
- j: with shock-absorbing device;
- k: with 2 axles highest load limit under 20 t, with 4 axles highest load limit under 40 t, with 6 axles or more highest load limit under 50 t;
- kk: with 2 axles highest load limit between 20 t and 25 t, with 4 axles highest load limit between 40 t and 50 t, with 6 axles or more highest load limit between 50 t and 60 t;
- l: with bulk gravity unloading, on both sides, simultaneously, at the top;
- ll: with bulk gravity unloading, on both sides, simultaneously, at the bottom;
- m: with 2 axles inside length of the wagon under 9 m, with 4 axles or more inside length of the wagon under 15 m;
- n: with 2 axles highest load limit over 30 t, with 4 axles highest load limit over 60 t, with 6 axles or more highest load limit over 75 t;
- o: with axial bulk gravity unloading, at the top;
- oo: with axial bulk gravity unloading, at the bottom;
- p: with axial controlled gravity unloading, at the top;
- pp: with axial controlled gravity unloading, at the bottom.

U: special wagons (reference wagon: other than those in categories F, H, L, S or Z, with 2 axles highest load limit between 25 t and 30 t, with 3 axles highest load limit between 25 t and 40 t, with 4 axles highest load limit between 50 t and 60 t, with 6 axles or more highest load limit between 60 t and 75 t):
- a: with 4 axles;
- aa: with 6 axles or more;
- c: with unloading under pressure;
- d: with controlled gravity unloading, on both sides, alternately, at the top;
- dd: with controlled gravity unloading, on both sides, alternately, at the bottom;
- f: suitable for traffic with Great Britain;
- ff: suitable for traffic with Great Britain (by tunnel exclusively);
- fff: suitable for traffic with Great Britain (by train-ferry exclusively);
- g: for grain;
- i: fitted out for the transport of objects which should exceed the gauge if they were loaded on ordinary wagons;
- k: with 2 or 3 axles highest load limit under 20 t, with 4 axles highest load limit under 40 t, with 6 axles or more highest load limit under 50 t;
- kk: with 2 or 3 axles highest load limit between 20 t and 25 t, with 4 axles highest load limit between 40 t and 50 t, with 6 axles or more highest load limit between 50 t and 60 t;
- l: with bulk gravity unloading, on both sides, simultaneously, at the top;
- ll: with bulk gravity unloading, on both sides, simultaneously, at the bottom;
- n: with 2 axles highest load limit over 30 t, with 3 axles highest load limit over 40 t, with 4 axles highest load limit over 60 t, with 6 axles or more highest load limit over 75 t;
- o: with axial bulk gravity unloading, at the top;
- oo: with axial bulk gravity unloading, at the bottom;
- p: with axial controlled gravity unloading, at the top;
- pp: with axial controlled gravity unloading, at the bottom.

Z: tank wagon (reference wagon: with metal shell, for the transport of liquids or gases, with 2 axles highest load limit between 25 t and 30 t, with 3 axles highest load limit between 25 t and 40 t, with 4 axles highest load limit between 50 t and 60 t, with 6 axles or more highest load limit between 60 t and 75 t):
- a: with 4 axles;
- aa: with 6 axles or more;
- b: for oil products;
- c: with unloading under pressure;
- d: for food and chemical products (only applicable to 1520 mm gauge wagons);
- e: fitted with heating devices;
- f: suitable for traffic with Great Britain;
- ff: suitable for traffic with Great Britain (by tunnel exclusively);
- fff: suitable for traffic with Great Britain (by train-ferry exclusively);
- g: for the transport of gases under pressure, liquefied or dissolved under pressure;
- i: tank of non-metallic material;
- j: with shock-absorbing device;
- k: with 2 or 3 axles highest load limit under 20 t, with 4 axles highest load limit under 40 t, with 6 axles or more highest load limit under 50 t;
- kk: with 2 or 3 axles highest load limit between 20 t and 25 t, with 4 axles highest load limit between 40 t and 50 t, with 6 axles or more highest load limit between 50 t and 60 t;
- n: with 2 axles highest load limit over 30 t, with 3 axles highest load limit over 40 t, with 4 axles highest load limit over 60 t, with 6 axles or more highest load limit over 75 t;
- p: with station for brakeman.