The Hamilton and Norwood male pattern baldness classification systems are comprehensive and involve several stages. However, the distinction between the different patterns for different ethnic groups is not always clear. Some trichologists, especially in Europe, use in addition a simpler five stage classification system developed by Rook and Ebling. This system is rarely used in medical research as it is not detailed enough, but the five stage classification is useful for explaining hair loss to patients. This simplified classification is easier to comprehend. In addition, Ebling developed several classifications for particular ethnic groups and these may be more relevant to some patients than the Hamilton and Norwood "catch-all" classifications. Three schemes under the classification of Rook-Ebling are presented down below for most European man - Mediterraneans or Latins, Jews or Arabs and from Nordic countries. Thus, the Mediterranean or Latin development of pattern baldness involves recession of the frontal hairline and the development of vertex baldness. These two regions of hair loss expand and unites into the extensive type V pattern. Though in the Semitic (Jewish, Arabian) presentation of pattern alopecia involves progressive recession of the frontal hairline but there is no associated thinning on the vertex. And finally the Nordic presentation differs with a central lock of surviving hair on the top of the head.