The transactions on the network (i.e. between the banks and the association) typically use the ISO 8583 protocol: https://en.wikipedia.org/wiki/ISO_8583 https:/

The transactions on the network (i.e. between the banks and the association) typically use the ISO 8583 protocol: https://en.wikipedia.org/wiki/ISO_8583 https://en.wikipedia.org/wiki/ISO_8583 The actual implementation (for e.g. between the hardware terminal and their gateway) is usually using some custom API/protocol - for e.g. Stripe/Braintree have their own APIs as do other older players like like PTI (https://www.chasepaymentech.com/developercenter/index.html?WT.mc_id=supernav_devcenter https://www.chasepaymentech.com/developercenter/index.html?W...).