The difficulties of Wiener's Rh-Hr nomenclature have frequently been emphasized, and many workers in the field have been led to use the Fisher-Race C-D-E notations on the grounds that the latter are self-explanatory and simpler to use and teach. Actually, any problem which may exist is not with the Rh-Hr nomenclature but with the subject matter, which is indeed complex. The Rh-Hr nomenclature is by no means as difficult as has been claimed; in fact, by using the Rh-Hr nomenclature workers can gain insight into the subject such as is not possible with the C-D-E notations. In this article, therefore, I propose to explain some of the principles underlying blood grouping nomenclature in general, and Rh-Hr nomenclature in particular, and shall demonstrate how the use of the most appropriate nomenclature facilitates one's mastery of what may appear to be a complex subject.
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