Symbols and abbreviations

Abbreviation Meaning Context Description
APDU Application-level Protocol Datagram Unit A command sent by an application to a card (C-APDU) or a response sent back by the card (R-APDU)
ATR Answer To Reset ISO/IEC 7816 The initial string sent spontaneously by a smart card upon reset
BLE Bluetooth Low Energy A subset of the Bluetooth 4.x standard that is optimized for low power devices
CCID Chip Card Interface Device The USB class specification for PC/SC readers
CID Card IDentifier ISO/IEC 14443-4 Allows a contactless reader to operate multiple cards simultaneously
DEP Data Exchange Protocol ISO/IEC 18092
DID Same as CID but in NFC standards
ICC Integrated Circuit Card One of the standard names for a smart card
IFD Interface Device One of the standard names for a smart card reader
IFSC Information Field Size for ICC ISO/IEC 7816, T=1 protocol Negotiates the size of the blocks from the reader to the card
IFSD Information Field Size for IFD Negotiates the size of the blocks from the card to the reader
GATT Generic ATTributes Bluetooth Hierarchical structure that exposes a BLE device's data and methods
GAP Generic Attributes Protocol Bluetooth Bluetooth's function to discover a device's features
NAD Node Address ISO/IEC 7816, T=1 protocol
ISO/IEC 14443-4
An option in T=1 and T=CL to open numerous virtual communication channel with a single card
PPS Protocol and Parameters Selection ISO/IEC 7816 Negotiates the card/reader protocol and bitrate
RFU Reserved for Future Use
TPDU Transport-level Protocol Datagram Unit In block-oriented protocols (T=1, T=CL), a single block
USB Universal Serial Bus