Does somebody have good resources on what a digital dollar would even mean? The dollar already digital, most dollars are held at banks, which are in turn held a

Does somebody have good resources on what a digital dollar would even mean? The dollar already digital, most dollars are held at banks, which are in turn held as entries at the Fed. How does a digital dollar change any of this? Why is a blockchain better than a plain old relational database somewhere in a Fed datacenter?