A phone that pays at a till must never pay the till next door. How Mizan BLE picks the nearest host by smoothed signal strength, what a real iPad and iPhone measured, why the first picker flickered at arm's length, and what iOS does not let a Bluetooth payment do.
A payment over Bluetooth has one way to succeed and many ways to stop. How Mizan BLE splits each side into a chain of state machines, why the countdown stops once the amount is sent, and how an iPad ends a link it is not allowed to close.
Mizan BLE is a proof of concept in which an iPad at the till and a payer's iPhone agree a payment over Bluetooth Low Energy. What it is, which device plays which Bluetooth role, and how the four characteristics of one service carry a whole transaction.