Adams County, Ohio Ahnentafels
An ahnentafel is a genealogical numbering system for listing a person's direct ancestors in a fixed sequence of ascent. The subject of the ahnentafel is listed as No. 1, the subject's father as No. 2 and the mother as No. 3, the paternal grandparents as No. 4 and No. 5 and the maternal grandparents as No. 6 and No. 7, and so on, back through the generations. Apart from No. 1, who can be male or female, all even-numbered persons are male, and all odd-numbered persons are female. In this schema, the number of any person's father is double the person's number, and a person's mother is double the person's number plus one. Using this knowledge of numeration, one can derive some basic information about individuals who are listed without additional research. This construct displays a person's genealogy compactly, without the need for a diagram such as a family tree. It is particularly useful in situations where one may be restricted to presenting a genealogy in plain text, for example, in e-mails or newsgroup articles. In effect, an ahnentafel is a method for storing a binary tree in an array by listing the nodes in level-order