Genealogical numbering systems
There are several widely adopted genealogical numbering systems for depicting a family tree or pedigree chart in text format.
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Ahnentafel
The number of a person's father is the double of their own number, and the number of a person's mother is the double of their own, plus one. For instance if the number of John Smith is 10, his father is 20, and his mother is 21.
The first 15 numbers are as follows:
1 self 2 father 3 mother 4 father's father 5 father's mother 6 mother's father 7 mother's mother 8 father's father's father 9 father's father's mother 10 father's mother's father 11 father's mother's mother 12 mother's father's father 13 mother's father's mother 14 mother's mother's father 15 mother's mother's mother
Register Numbering System
The Register Numbering System uses both common numerals (1, 2, 3, 4) and Roman numerals (i, ii, iii, iv). Generations are grouped separately.
The system was created in 1870 for use in the New England Historic and Genealogical Register published by the New England Historic Genealogical Society. Register Style, of which the numbering system is part, is one of two major styles used in the U.S. for compiling descending genealogies. (The other being the NGSQ style.)<ref name="curran">Curran, Joan Ferris, Madilyn Coen Crane, and John H.Wray.Numbering Your Genealogy: Basic Systems, Complex Families, and International Kin. Arlington, Virginia: National Genealogical Society, 1999.</ref>
NGSQ Numbering System
The NGSQ Numbering System gets its name from the National Genealogical Society Quarterly, which uses the numbering system. It is sometimes called the Record System, or the Modified Register System because it derives from the Register Numbering System.
Henry Numbering System
The Henry Numbering System is a descending system created by Reginald Buchanan Henry. The system begins with 1. The oldest child becomes 11, the next child is 12, and so on. The oldest child of 11 is 111, the next 112, and so on. The system allows one to derive an ancestor's relationship based on their number. For example, 621 is the first child of 62, who is the second child of 6, who is the sixth child of 1.
In the Henry system, when there are more than nine children, X is used for the 10th child, A is used for the 11th child, B is used for the 12th child, and so on. In the Modified Henry system, when there are more than nine children, numbers greater than nine are placed in parentheses.
Henry Modified Henry
1. Progenitor 1. Progenitor
11. Child 11. Child
111. Grandchild 111. Grandchild
112. Grandchild 112. Grandchild
12. Child 12. Child
121. Grandchild 121. Grandchild
122. Grandchild 122. Grandchild
123. Grandchild 123. Grandchild
124. Grandchild 124. Grandchild
125. Grandchild 125. Grandchild
126. Grandchild 126. Grandchild
127. Grandchild 127. Grandchild
128. Grandchild 128. Grandchild
129. Grandchild 129. Grandchild
12X. Grandchild 12(10). Grandchild
d'Aboville System
d'Aboville is a descending system very similar to the Henry system. It differs in that periods are used to separate the generations and no changes in numbering are needed for families with more than nine children.Encyclopedia of Genealogy: d'Aboville Numbers For example:
1 Progenitor
1.1 Child
1.1.1 Grandchild
1.1.2 Grandchild
1.2 Child
1.2.1 Grandchild
1.2.2 Grandchild
1.2.3 Grandchild
1.2.4 Grandchild
1.2.5 Grandchild
1.2.6 Grandchild
1.2.7 Grandchild
1.2.8 Grandchild
1.2.9 Grandchild
1.2.10 Grandchild
This system was developed by Count Jacques d'Aboville]] in 1940 and is widely used in France. Les systèmes de numérotation (Numbering Systems)
de Villiers/Pama System
The de Villiers/Pama System gives letters to generations, and then numbers children in birth order. Therefore c4 is the fourth grandchild and d3 is the third great grandchild. For example:
a Progenitor
b1 Child
c1 Grandchild
d1 Great grandchild
d2 Great grandchild
c2 Grandchild
c3 Grandchild
b2 Child
c1 Grandchild
c2 Grandchild
c3 Grandchild
The de Villiers/Pama system is the standard for genealogical works in South Africa. It was developed in the 19th century by Christoffel Coetzee de Villiers and used in his three volume Geslachtregister der Oude Kaapsche Familien (Genealogies of Old Cape Families). The system was refined by Dr. Cornelis (Cor) Pama, one of the founding members of the Genealogical Society of South Africa.Genealogical Society of South Africa
