Other than astronomic (stars' masses are known more precisely in sun's masses than in kilograms), atomic (charges are integral numbers of elementary charges but unround numbers of coulombs), and angular (angles are often expressed as turns divided by an integer rather than radians), are there kinds of data that should be stored in non-metric units?
Suppose you're writing a software program that handles measurements, and the data have been expressed in both metric and non-metric units. How do you handle input, storage, and output of data? I'm writing a surveying CAD program called Bezitopo. All data are stored in floating-point coherent SI units, except angles, which are stored in fixed-point 2^-31 turns, unless they're defining a position on the earth, in which case they will probably be stored as floating-point radians. Lengths can be input or output in meters, international feet, US survey feet, or Indian survey feet, but they are always stored in meters. LandXML has a tag that says what units measurements will be stored in. They can all be meters, or they can all be (US or international) feet. Pierre -- La sal en el mar es más que en la sangre. Le sel dans la mer est plus que dans le sang.
