Negotiable Bill of Lading Example 1: "To Order" and Blank Endorsed

According to Incoterms 2010 FOB, CFR, CIF trade terms rules, the seller is required either to deliver the goods on board the vessel or to procure goods already so delivered for shipment.

The reference to “procure” here caters for multiple sales down a chain (‘string sales’), particularly common in the commodity trades.

Above definition explains seller's delivery obligation under FOB, CFR and CIF trade terms according to Incoterms 2010 rules. As mentioned on the 1st paragraph, incoterms rules allow multiple sales or string sales.
But what sort of bill of lading the seller (exporter) should supply to his buyer, which becomes the new seller and trades the same goods to another potential buyer with the same bill of lading?