What is an ahnentafel number?

My Reunion 6 manual says, quote: "The ahnentafel numbering system assigns the number 1 to the source person. The father of number 1 is number 2. The spouse of 2 is 3. The rule is: to find the father of a person, double the number. To find the mother of a person, double the number and add 1. "

So I'm 1, my dad is 2, mom is 3; dad's parents are 4 (grandpa) and 5 (grandma), etc, etc, If you don't have a name for the person who goes there, you leave it blank and skip the number, because -- well, let's face it, you HAD to have had an ancestor there, even if you don't know who it was!

If you have a loop in your tree (multiple lines of descent from the same person, or inbreeding if you prefer) the same person gets more than one ahnentafel number. For example, in my tree, Erni Betschart (1490 -), my 13g-grandfather, occupies ahnentafel numbers 32,768 and 34,816, because I trace my descent through two of his descendants, the brothers Ulrich and Melchior Betschart.

The number of people in each generation doubles, and there's no limit to ahnentafel numbering -- except the practical limit of running out of ancestors' records. The grandchildren of one of my cousins on my dad's side have Erni Betschart as their 15g-grandfather, and he occupies numbers 147,456 and 149,504 in their charts. Now if we can just find a sheet of paper that big ...