UCC-1 form filing from Book 1 redemption series 5.0 page 403 #4 Collateral Box info – Birth Certificate numbers

In reviewing the UCC-1 example page 403, and on page 378 under the RE: portion an account number is referenced in both places around (8) digits long and follows the birth certificate numbers... (ie 131-458754/15487542) what do these numbers represent? Are these the numbers on the bottom left hand corner on the BC also under the WARNING: ? Is this a "subaccount" ? We understand the accounts for the SS# and the numbers on the back of the SS# and the birth certificate number with the starting 3 numbers on the top right of the form (usually) but do not know where the other set of numbers is from or is referencing. (the 15487542) Can you please advise or point us in the right direction in the 5 series books. Currently we have books 1 through 3 of 4.