Four terminologies are recognized to describe phenotypic expression in the Rh blood group system. Two of these use theories of inheritance to define nomenclature related to the system. A third terminology uses the presence or absence of the antigens and an alphanumeric notation, while the fourth utilizes a numbering system that is more suitable for digital/computer platforms.
The following pages will describe each of the terminologies, how they are used in practical application, and the interchangeable use of the nomenclature.
