Hi,
Its the sexes.
Stands for male,female and unknown.
So if you have a boy and one you have had sexed yet it would be 1.0.1
And if you had a little girl it would be 0.1.0 - but if the last number is zero most people just leave it out so it becomes 0.1.
**edit**
Doh!!! waaaaay to slow.
**end edit**
dr del