upstream
It is dedicated, private interbank telecommunication infrastructure by which banks process payments ("authenticate" account balances, record transactions, and transfer "money" between any and all account owners at banks in different countries, which pay a subscription to the Society for Worldwide Interbank Financial Telecommunications.

downstream
Central banks regulate national, closed-loop intrabank payments such as RBA and ACH and  or CHIPS according to legislated capital controls as to Reasons®.

No funds--for any reason? No transfers.

Contrary to libertarian folklore, "digital currency" has been circling the globe since US-UK laid the first transnational, under-sea cables to lock up mutually beneficial imperial assets.

Scott and Zachariadis, "Origins and Development of SWIFT, 1973-2009"

Go First Bank of America fourth life!