ACL - Access Control List. A set of permissions stored in the tag’s memory sectors (trailer block with keys and access bits).
ACL - Allocation Class. Fixed 8-bit value in MSB of block 1 page 1 that helps categorize the organization responsible for allocating UIDs to the tags. E0h is the value for ATA5577. ISO/IEC 15963-1.
AFE - Analog Front End. All circuits that are directly connected to the coil terminals in the transponder.
AFI - Application Family Indicator. Memory block in the upper part of the tag's memory that identifies the tag's application area. Some manufacturers use the AFI code for security purposes.
Anti-Collision - Technology that prevents multiple tags from interfering with each other when they are read simultaneously.
ATA5577 (ATA5577C, T5577). R/W IC found in LF tags - can emulate other LF formats.
ATQA - Answer To Request (acc. to ISO/IEC 14443-4)
ATS - Answer To Select (acc. to ISO/IEC 14443-4)
AWID - Applied Wireless Identification Group. Manufacturer of RFID products such as proximity cards, key fobs, vehicle tags and readers.
B
Bi-phase - modulation. A method used by the transponder (tag) to send data back to the reader.
C
CID - Chip ID. 5-bit field, specifically bits 17 to 21 in block 1 page 1, used to distinguish between different variations or specific models within the broader ATA5577 family of integrated circuits (00001b for ATA5577M1, 00010b for ATA5577M2).
CL - Cascade Level (acc. to ISO/IEC 14443-3)
COS - Card Operating System
Cotag. Dual-technology LF tags, that combine active (battery-powered) and passive technology.
CRC - Cyclic Redundancy Check. Error-detection method that generates a short, fixed-length value called a checksum to verify the integrity of digital data.
CT - Cascade Tag, Type A
CUID - Changeable Unique Identifier. Special type of identifier used on certain tags, where the normally fixed UID can be modified.
D
DIF - Dual Interface (cards)
E
EM4100
EM410x
EM4x05
EEPROM - Electrically Erasable Programmable Read-Only Memory. Type of non-volatile memory that retains data even when power is turned off
F
FDX-B
FlexPass
FSK - Frequency Shift Keying - modulation. A method used by the transponder (tag) to send data back to the reader.
G
H
HF - High Frequency
I
ICR - IC Revision. 3-bit field, specifically bits 22 to 24 in block 1 page 1, used for the IC and/or foundry version of the ATA5577.
IDIC - Identification Integrated Chip (Identification Integrated Circuit). Specific types of integrated circuits used in RFID applications, primarily operating in the LF range.
J
K
L
LF - Low Frequency
M
Manchester - modulation. A method used by the transponder (tag) to send data back to the reader.
MFC - Manufacturer Code. Second byte of block 1 page 1. Value 15h is for Atmel/Microchip. ISO/IEC 7816-6.
MSB - Most Significant Byte. The byte in a multi-byte number that has the greatest weighted value or influence on the total value of that number.
N
NDEF - NFC Data Exchange Format
NFC - Near Field Communication
NRZ - Non-Return-to-Zero - modulation. A method used by the transponder (tag) to send data back to the reader.
NUID - Non-Unique Identifier. Tag identifier that is not guaranteed to be globally unique.
Proximity tag (proximity card, prox card, key card, keycard). Original 125 kHz tag without a smart chip, that doesn't hold more data than a magnetic stripe card.
PSK - Phase Shift Keying - modulation. A method used by the transponder (tag) to send data back to the reader.
Q
R
REQA - Request Command, Type A
RFID - Radio Frequency Identification
RFU - Reserved for future use
RID - Random ID, typically dynamically generated at Power-on Reset (UID0 = “0x08”, Random number in UID1… UID3)
S
SAK - Select Acknowledge, Type A
Select - Select Command, Type A
T
T55xx
U
UHF - Ultra High Frequency
UID - Unique Identifier, Type A. A unique number assigned to each RFID tag by the manufacturer.
V
Vicinity tag (Vicinity card, VICC). Contactless HF RFID tags designed for longer reading ranges compared to proximity tags. Based on ISO/IEC 15693 standard developed by ISO/IEC JTC 1/SC 17 committee.