Oldham-Rutherford rule

Oldham and Rutherford s Rule does not apply to, nor was it propounded for, non-cyclic alditol derivatives. Neither does it apply to that part (if any) of a cyclic-sugar molecule which is actually an appended, non-cyclic alditol chain. Thus, it does not apply to carbon atoms 5 and 6 of an aldohexofuranose nor, presumably, to carbon atoms 6 and 7 of an aldoheptopyranose or carbon atoms 5, 6, and 7 of an aldoheptofuranose. 

---