I am in the process of naming Diels Alder cycloaddition products, where it is necessary to distinguish between four possible structural isomers.

With reference to a characteristic group, the compound is named. One way would be name it based on whether the group is endo or exo wrt the bridge, and another way would be to assign R/S to the carbon bearing that group.

Which method is preferred in IUPAC?

Thanks.