d'Aboville Numbers

Developed by Count Jacques d'Aboville in 1940, this numbering system is widely used in France.  d’Aboville numbers are almost the same as Henry Numbers, except that each digit (or double digit for numbers larger than 9) is separated by a period. Thus the first child of No. 1 is 1.1; the 10th would be 1.10. The first children of the latter would be 1.10.1. As a result, the d’Aboville Numbers are better at handling more than nine children in a family than Henry Numbers. The tenth child is number ten, the eleventh is number eleven, etc. The periods make it easier to read the number correctly. A minor variation sometimes seen in American publications is the use of a hyphen instead of a period.

See Numbering Systems