The register system is a standardized [System numbering system] for the descendants of an individual. In this system, the first person is assigned the number 1. His or her children are then listed in birth order, indented and identified by lower-case letters (a, b, c, etc.). The children who have documented descendants are also given an Arabic number, which is written to the left of their birth order letter. The numbers then begin to resemble an outline. This simplifies the tracing of all descendants of the start person through their unique numbers.
The New England Historic Genealogical Society of Boston, Massachusetts, created the register system for use in its publication, the New England Historical and Genealogical Register.
See Register Style