Sentence:  In order to prevent consumers from supplementing their current cash allowance out of cash hoards, it would be necessary either to stamp all dollar bills when the scheme is put into operation or to change them completely; e.g., by printing "<WSD>brownbacks</WSD>" instead of "greenbacks." 
Meaning of the word marked with <WSD> tags:  A note of scrip printed on brown paper, such as that issued by the city of St. Louis during a financial crisis.