Ahnentafel

Using this definition of numeration, one can derive some basic information about individuals who are listed without additional research.

In effect, an ahnentafel is a method for storing a binary tree in an array by listing the nodes (individuals) in level-order (in generation order).

The ahnentafel system of numeration is also known as the Eytzinger Method, for Michaël Eytzinger, the Austrian-born historian who first published the principles of the system in 1590;[1] the Sosa Method, named for Jerónimo (Jerome) de Sosa, the Spanish genealogist who popularized the numbering system in his work Noticia de la gran casa de los marqueses de Villafranca in 1676;[2] and the Sosa–Stradonitz Method, for Stephan Kekulé von Stradonitz, the genealogist and son of chemist Friedrich August Kekulé, who published his interpretation of Sosa's method in his Ahnentafel-atlas in 1898.

For instance, someone can find out what number Sophia of Hanover would be on an ahnentafel of Peter Phillips (son of Princess Anne and grandson of Elizabeth II).

So, we multiply and add: Thus, if we were to make an ahnentafel for Peter Phillips, Electress Sophia would be #7233, among other numbers due to royal intermarriage causing pedigree collapse.

William, Prince of Wales (born 21 June 1982) An ancestor may have two or more numbers due to pedigree collapse.

In the German language, the term Ahnentafel may refer to a list of coats of arms and names of one's ancestors, even when it does not follow the numbered tabular representation given above.

In this case, the German "Tafel" is taken literally to be a physical "display board" instead of an abstract scheme.

In Nazi Germany, the Law for the Restoration of the Professional Civil Service required a person to prove non-Jewish ancestry with an Ariernachweis (Aryan certificate).