Rule 10.5 clarification

[c-addison]

The description of rule 10.5 mentions that the operators must be applied to "small integer types" for the casts to be required. The types unsigned char and unsigned short are mentioned explicitly. What if char, short, and int are all the same size on the machine? In that case is OK to not perform the required cast? This really comes down to whether or not we should be checking for the unsigned char and unsigned short types explicitly or instead should check for all types which have a a narrower type than int.