surfer200 & IRstuff - there is a similar problem in both cases with non-SI compound return units. The program can handle input made up of any combination of recognised input units (including kg, kgf, and m with any prefix), but if these combine to make a unit that is not in the list it can't break down the compound non-SI units into their constituent parts. The solution is to add more units to the non-SI list.
For stressess I will certainly add kgf/cm2, kgf/m2, and also kgf.cm and kgf.m for moments. At the moment I don't intend to add ton/m2 and ton.m because of the numerous different "ton" definitions. Note that the "tonne" (1000 kg) is already listed as a unit of mass, but a tonne.m will not be a recognised unit of bending moment, so you won't be able to convert lbf ft to tonne.m, but you will be able to go from lbf ft to kgf.cm.
For specific heat I will add common non-SI units to the list, but they won't include BTU.kg-1.K-1 or other mixed systems (unless there are examples of mixed units in common use).
Regardless of what I add to the list, it is editable, so people can add whatever they like. I'll describe the procedure for doing that in my next blog post on the units topic.
Thanks for the feedback.
Doug Jenkins
Interactive Design Services
