Genealogical numbering systems

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There are several widely adopted genealogical numbering systems for depicting a family tree or pedigree chart in text format.

Contents

1 Ahnentafel
2 Register Numbering System
3 NGSQ Numbering System
4 Henry Numbering System
5 d'Aboville System
6 de Villiers/Pama System
7 Notes
8 References
9 See also

Ahnentafel

Ahnentafel, also known as the Sosa-Stradonitz system, allows for the numbering of ancestors beginning with a descendant. The system allows one to derive an ancestor's number without compiling the list and allows one to derive an ancestor's relationship based on their number.

The numbering is 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 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.)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.

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]

Notes

References

About.com: [Numbering Your Family Tree]
[Numbering Systems in Genealogy] by Richard A. Pence