interesting thought ping.
They were drafting before the 1st Draft Lottery in Dec 1969
I enlisted when I was 17 in Sept of 66.
I went in one day before my 18th birthday.
I was a "kiddie cruiser" which meant my enlistment ended
one day before my 21st birthday in Sept 69
Once I got out I still had to register with the Selective Service
In Dec 69, when the 1st birthday was drawn, it was my birthday Sept 14
Well since I had prior service I was IV-A
(Registrant who has completed service)