The parameter D in the convert unit templates specifies dimension. Base dimensions are encoded with prime numbers. Other dimensions are the corresponding products of the base units and/or their inverses. The table below lists the codes used. One hundred and one distinguishes scalars from vectors. Eleven is used to distinguish other dimensionally equivalent units which are conceptually different (e.g. pressure vs energy density).

number code dimension
1 numbers
2 length
3 mass
4 area
5 time
7 electrical current
8 volume
11 special code
13 angle
19 temperature
23 amount of substance
29 luminous intensity
31 currency
35 electrical charge
44 volume of fuel per unit distance
1/44 distance per unit volume of fuel
169 solid angle
3/8 density
1/5 frequency
8/5 volumetric flow
11/5 radioactive decays per unit time
2/5 speed
2/25 acceleration
6/25 force
3/50 pressure
12/25 energy
1212/25 torque
12/125 power
33/50 energy density
12/895 potential difference
101 vectors