Guide to Magnetic Encoding on Cards

According to ANSI & ISO/IEC Standards

The purpose of this guide is to give an overview of the magnetic encoding characteristics as defined by ANSI and ISO/IEC standards.

I. Magnetic Stripe Card Physical Configuration as Specified by ISO Standards: 7811-1 through 6, 7812, 7813, and 4951.

I.1 Magnetic Stripe Card Dimensional Characteristics

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I.2 Location of Encoded Data Tracks

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I.3 Standard Definition of Magnetic Tracks

The magnetic track assignments were made for specific industry uses, such as financial, thrift etc. and comprise the vast majority of cards in use, but not all. Other applications such as access control, identification, and driver’s licenses have developed their own custom formats for each track. This capability to reformat the content of each track has allowed magnetic stripe card technology to expand into many industries. The three magnetic tracks, defined for financial industry applications, have been assigned names and numbers as listed below:

Track 1: Developed by the International Air Transportation Association (IATA), track 1 contains alphanumeric information for automation of airline ticketing or other transactions where a reservation database is accessed.
Track 2: Developed by the American Bankers Association (ABA), track 2 contains numeric information for the automation of financial transac- tions. This track of information is also used by most systems that require an identification number and a minimum of other control information.
Track 3: Developed by the Thrift Industry, track 3 contains information, some of which is intended to be updated (re-recorded) with each transaction (e.g., cash dispensers that operate “off-line”).

I.4 Basics of Magnetics and Reading Coded Character Set Tables

A magnetic stripe is encoded with bit patterns, which correspond to alphanumeric (Track 1) or numeric (Tracks 2 & 3) ASCII characters. The number of bits on a given track is limited to a certain number of bits per inch, or BPI. There are also a series of all zero bits encoded at the beginning and end of a magnetic stripe; these “clocking bits” establish timing for the reader, or the time the reader will detect flux reversals as it moves down the magnetic stripe.

For each character in the bottom right section of the Track 1 Coded Character Set table, there is a bit pattern which consists of six bits. To determine this bit pattern for each character, read to the left of the character in its corresponding row, from bit 1 to bit 4. To determine bits 5 and 6, read above the character in its corresponding row. For example, the bit pattern for “D” (Column 2, Row 4) would be “0 0 1 0 0 1” plus odd parity bit = 1.

For the Tracks 2 & 3 Coded Character Set table (page 7), read to the left of each numerical character. For example, the bit pattern for “6” (row 6) would be 0 1 1 0 with odd parity (P).

II. Data Format for Financial Transaction Cards

II.1 Definitions

Bit - A binary digit with the value of either 0 or 1. Each track consists of a string of bits; bits strings make up an alpha or numeric character (see Coded Character Set tables).
End Sentinel - A defined character (bit pattern) in an encoding format. Cannot be used for data. The End Sentinel is encoded on the magnetic stripe immediately after the last data character and indicates the end of data.
Field Separator - A designated character which separates data fields. Cannot be used for data.
Format Code - Under ANSI/ISO Track 1 protocol there are two defined formats: Code A is name first; Code B is account number first. For Track 3, the first two digits identify the data format used.
Start Sentinel - A defined character (bit pattern) in an encoding format. Cannot be all zeros. The Start Sentinel is encoded on the magnetic stripe immediately before the first data character and indicates the beginning of data.
Parity - A self-checking code using binary digits in which the total number of ones (or zeros) in each track is always even or always odd. A check for even or odd parity detects errors in the system.
Longitudinal Redundancy Check Character- A bit pattern which is encoded immediately after the End Sentinel. Checks for bit errors in the message, which includes the Start Sentinel, End Sentinel, data, and field separators.

II.2 Track 1 (IATA)

Recording density (bits per inch) = 210 bpi
Character configuration (including parity bit) = 7 bits per character
Information content (max.) = 79 alphanumeric char.

Track 1 data reads:
<SS><FC><PAN><FS><CC><NAME><FS><Additional Data><CC><LRC>
where SS = Start Sentinel = %
FS = Field Separator = {
ES = End Sentinel = ?
FC = Format Code
LRC = Longitudinal Redundancy Check Character
CC = Country Code (3 characters minimum)
PAN = Primary Account Number (19 digits maximum)
NAME = 26 Alphanumeric Characters Minimum
Additional Data = *Expiration Data = 4
Interchange Designator = 1
Service Code = 2
Discretionary Data
*required by Visa and MasterCard
a. Track 1 is limited to 79 characters including Start Sentinel, End Sentinel and LRC.
b. MasterCard PAN varies up to 16 characters maximum.
c. Visa is 13 or 16 characters, including mod 10 check digit.
d. Italicized text identifies control characters.

Track 1 Coded Character Set:

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a. These characters are available for hardware control purposes only and cannot contain information characters.