When dimensioning a part in a different unit than what the document setting is set at, if the unit is spelled out in caps (MM) or (IN) an error pops up saying "the expression cannot be evaluated". It would be helpful if Inventor would give a default option in the error message to override the all caps MM and replace it with the lowercase unit. This way the error message still pops up, but hitting enter on the keyboard would accept the change. This would still allow an uppercase version of the unit to still work as a user parameter if someone has it set up that way.
