Quote Originally Posted by mikecz View Post
I'm thinking now United States currency notes are indeed lawful money, but, there are other types of lawful money. Coin being one of them.
US Treasuries and agency treasuries are considered lawful money.

In fact, these are the underpinnings of FRNs currently.

Essentially, commercial paper issued by the Department of the Treasury and other US governmental agencies are the lawful money supporting the issuing of FRNs.