I don't know about any of the other stuff, date codes ,PO stamps and what have you . But in the link Watchman posted there is reference to the
"a. The 10-character Document Locator Number (DLN) was placed on Selective Service Registration Forms beginning prior to the establishment of our current Data Management Center on 31 August 1981."
However the typed number is 11 digits,
(I can't get it to copy but it's DS's item A in M'ette's link )
Also, My SSS# was registered in 1985 and starts 60 (date of birth ) 20XXXXX-X, Obama's was registered in 1980 wit a number 61 (DOB ) 11XXXXX-X is there a way to check if more than 900,000 people registered in 5 years, out of a population of over 200 million that seems low, about .1% of the population per year.