A racemic mixture must result in this situation. However, attack at an enantiotopic face by a chiral reagent gives diastereomers, which are not formed in equal amounts. (3) In a case like 103, the two faces are obviously not
equivalent and are called diastereotopic. Enantiotopic and diastereotopic faces can be named by an extension of the Cahn–Ingold–Prelog system. If the three groups as arranged by the sequence rules have the order X > Y > Z, that face in which the groups in this sequence are clockwise(as in 104) is the Re face (from Latin rectus), whereas 105 shows the Si face (from Latin sinister).