Sub-/superscript w/o blank
Subscript and superscript works fine in all redmine text areas, but only if you put a blank between the normal and the subscript text.
You can't write proper units at the moment and have to use e.g. CO 2 , m 2
Although, it is part of the textile standard. It should be written e.g. as CO[~2~] m[^2^] and it's listed in the linked long help text.