DEFINITION of 'Base I'
The data processing network used by Visa USA to process and provide authorization and authorization-related services for credit card transactions that occur through banks that are connected with Visa USA.
BREAKING DOWN 'Base I'
Base I was created in 1976 by Bank of America's IT staff. BASE stands for Bank of America System Engineering. The system was given this name because prior to 1973, Visa was known as BankAmericard.