ISO 14443

This international standard defines the PCD/PICC communication scheme. It is divided into 4 layers:
1. Defines the hardware characteristics of the PICC,
2. Defines the carrier frequency and the bit-level communication scheme,
3. Defines the frame-level communication scheme and the session opening sequence (anti-collision),
4. Defines the transport-level communication scheme (sometimes called “T=CL”).
The application-level is out of the scope of ISO 14443. Most microprocessor-based PICCs implement ISO 7816-4 on top of ISO 14443-4.
A lot of wired logic PICCs (NXP Mifare family, ST MicroElectronics ST/SR families, to name a few) implements only a subset of ISO 14443, and have their own set of functions on top of either ISO 14443-2 or ISO 14443-3.
Note that ISO 14443-2 and ISO 14443-3 are divided into 2 protocols called 'A' and 'B'. A PCD shall implement both, but the PICCs implement only one of them1. Four communication baudrates are possible: 106 kbit/s is mandatory, higher baudrates (212, 424 or 848 kbit/s) are optional.