Yes there IS . . . and it's on my blog somewhere and I don't have time to find it. There is a % rule for people who wish to classify themselves by race. A person must have a great-grandparent who is a full-blood of that race/ethnicity to claim to be that race/ethnic group.
Barack SENIOR had a great-grandparent who was Negroid making him 1/8 Negroid. He only passed 1/16 of that to his son. Technically, legally, Barry Dunham is not "black" by the percentage of Negoid blood. He is Caucasoid.
http://racialreality.110mb.com/subraces.html
East African: In the deserts and highlands of Ethiopia, Eritrea, and the Somalilands is found a concentration of several related Mediterranean types, mixed in varying degrees with negroes. To the west these partial whites border on Sudanese negroes; to the southwest the partially Hamitic tribes of Kenya and Uganda form art extension of the peripheral Mediterranean racial area. To the north, the Beja-Bisharin group of Hamitic-speaking nomads connect the East African Hamitic-speaking peoples with their wholly white Egyptian and Berber relatives of North Africa.
This is Barry Dunham Obama Zero's race.
http://racialreality.110mb.com/skincolor.html
Pigmentation is the most readily visible signifier of race, and as such it's often used by laymen to detect bi-racial ancestry. Yet it's also the least reliable from this standpoint, as it changes in response to climatic and environmental conditions, both seasonal and long-term, and can vary greatly within genetically differentiated populations (i.e. races).