Why petty cash?

 For me and my grocer. 

We run our own mini Swift hierarchical, proof of stake system.  We can clear accounts and reference the banker above us once a month. We are still in the Swift system. My account offer free cash without the ATM fee.

But it requires his spiral notebook.  All we are asking is for mini Swift codes for our cash cards.  Then I can grab my groceries and hit the red or green button.