If I'm reading this correctly, the debt instrument is akin to a battery. When the debt is "charged", the borrower has given it "currency" by agreeing to pay it off in the future. As the debt is payed off, currency is drained from the battery and put to work as economic energy. When it is fully paid off, it has expended all of its potential energy.
But when the borrower cannot repay the debt, it is "discharged" and thus no longer has "currency". However, it is still a battery capable of carrying a charge in the future.
Why your sheriff is the supreme law of the land