1st Export > 17,000 USD/T, page-407

Apparently, the serial number sequence isn't specific to SDJ,

From what I gather, the serial format (##/###/EC##/#####-A) is ordered year/province/customs office#/export#
And looking at a busier office in Salta:
17-053-EC01-000025-C = Boric Acid (Borax Argentina)
17-053-EC01-000086-J = Lithium Carbonate (FMC)
17-053-EC01-000088-L = Lithium Chloride (FMC)
17-053-EC01-000099-N = Borax Penta/Deca-Hydrate (Borax Argentina)

So the two records between 7A and 10R could be anything (other than lithium or borax products - I checked ), it just seems odd because we've had a monopoly on exports from the lonely 031-EC03 customs office.