This document discusses FeliCaTter, an SDK for FeliCa that allows communication between FeliCa cards and Adobe AIR or Flash applications. It can perform operations like polling, reading/writing, and authentication. The SDK uses FeliCaProxy to interface between the FeliCa DLL and ActionScript code. Developers can access features like user ID, payment method from FeliCa cards to integrate with services like Twitter.