Adding Custom Conversions

The conversions file is very similar to the constants file. The file containing all the conversions is the units.dat file. This file proceeds like so:
Group :=****STANDARD****
Group Name
metric
the standard metric unit
english
the standard english unit
the number of standard metric units in one standard english unit
[unit name
metric | english
the number of this unit in one of the standard unit of its type]*

Conclusion, same as the constants file. Do whatever you want, just backup first. Looking at the file is the easiest way to understand it.