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.

1 Ahnentafel
2 Register Numbering System
- 2.1 NGSQ Numbering System
3 Henry Numbering System
- 3.1 d'Aboville System
4 de Villiers/Pama System
5 Notes and references
6 See also
7 External links

[edit] Ahnentafel

Main article: 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 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

[edit] 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.)^[1]

[edit] 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.

[edit] 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

[edit] 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.^[2] 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.^[3]

[edit] 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.^[4]

[edit] Notes and references

^ 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.
^ Encyclopedia of Genealogy: d'Aboville Numbers
^ Les systèmes de numérotation (Numbering Systems)
^ Genealogical Society of South Africa