智能IC卡国际标准。非接触通讯协议，第三四部分。14443-4，描述防冲突，SAK等一，以及如何区分M1和CPU。-Smart IC card with international standards. Non-contact communication protocol, the third of four parts. 14443-4, describes the anti-collision, SAK other one, and how to distinguish between the M1 and CPU.