I guessed that the field was broken up into the subfields suggested by "xxyyzzz". The purported-to-be-Obama's middle sequence is 1125539. My son's number is lower than that but in the same ballpark. Yet they are on opposite parts of the country and Obama is twenty two years older. So there's a strangeness there.
I tried to check my own selective service number, but the on-line records only are available for those born on/after 1/1/1960.
What year was your son born in? I have been wondering if the 61 in the BO number is for year of birth.
Also can’t the office who records the registrations be contacted directly so they can explain the meaning of the coding that is currently being used?
Also if the coding has been recently changed does that also indicated that BO made a rather recent registration?
Aint that a good guess?