From: cooper@cbnewsg.cb.att.com (Ralph 'Hairy' Moonen)
Subject: Re: Magnetic Keycards
Organization: AT&T
Date: Tue, 15 Dec 1992 13:22:03 GMT


Hi, I hope this is the information you're lookin for:

----------------------------------------------------------------------
Following is a transcription of the magnetic data encoding standards as used
on ATM cards, credit cards and other Magnetic strip cards.

Track:		Density:	bits/char:		total chars on track:
-----------------------------------------------------------------------------
Track 1		210 bpi		7 bits/char		79 alphanum. chars
Track 2		75 bpi		5 bits/char		40 numeric chars
Track 3		210 bpi		5 bits/char		107 numeric chars

7 bit/char characters consist of a parity bit, followed by 6 data bits
5 bit/char characters consist of a parity bit, followed by 4 data bits

******************************************************************************
Track 1 as defined by the IATA: 
______________________________________________________________________________
| SS | FC |    PAN   | FS |    NAME      | FS |    Additional data  | ES |LRC|
------------------------------------------------------------------------------
          | Primary  |    | Name.        |__  |*Expir. date        4|
          | Account  |    | 26 alphanumeric|  |*Restriction/type   3|
          | Number   |___ | characters max |  |*Offset or PVN      5|
          | 19 dig. max | ------------------  | Discretionary data  |
          ---------------                     -----------------------
                                                                   ^
SS = Start Sentinel (= "%")                                        |
FS = Field Separator (= "{")                                 no. of chars
ES = End Sentinel (= "?")
FC = Format Code
LRC= Longitudinal Redundancy Check

* = Required by Visa and Mastercard.

Note: Mastercard PAN is variable upto 16 digits length, VISA 13 or 16 
digits, including mod 10 check digit.
******************************************************************************
Track 2 as defined by the ABA: 
______________________________________________________________________________
| SS |         PAN              | FS |         Additional data      | ES |LRC|
------------------------------------------------------------------------------
     |      Primary             |    |*Expiration date      4       |
     |      Account             |    |*Restriction or type  3       |
     |      Number              |    |*Offset or PVN        5       |
     |      19 dig. max         |    | Discretionary data           |
     ----------------------------    --------------------------------
                                                            ^
SS = Start Sentinel (= 0xb)                                 |
FS = Field Separator (= 0xd)                            no. of chars.
ES = End Sentinel (= 0xf)
LRC= Longitudinal Redundancy Check

* = Required by Visa and Mastercard.

Note: Mastercard PAN is variable upto 16 digits length, VISA 13 or 16 
digits, including mod 10 check digit.
******************************************************************************
Track 3 as defined by the TTS:  (ISO 4909)
______________________________________________________________________________
| SS | FC |    PAN   | FS |USE AND SECURITY DATA |   Additional data  |ES|LRC|
------------------------------------------------------------------------------
          | Primary  |    |*country code  3 or FS|*First Subsidiary   |___
          | Account  |    | currency code 3      | account number (SAN-1)|
          | Number   |___ | currency exponent 1  |___                    |___
          | 19 dig. max | | Amount auth. per cycle 4|_____*Second subsidiary|
          --------------- | amount remaining this cycle 4| account number   |
                          | Cycle begin(validity date   4| (SAN-2)          |
                          | Cycle length                2|                  |
                          | Reentry count               1| Relay Marker  1  |
                          |*PIN control param.  6 or FS  |                  |
                          | Interchange control         1|*Cryptogr. check  |
                          | PAN service restriction     2| Digits  6 or FS  |
                          | SAN-1 service restriction   2|                  |
                          | SAN-2 service restriction   2| Discretionary    |
                          |*Expiration date     4 or FS  | Data.            |
                          | Card sequence number        1|-------------------
                          |*Card security number 9 or FS |
                          --------------------------------
                                                        ^
                                                        |_no. of chars.

* This field is optional. If an optional field is not used, a field separator
  must be encoded.

SS = Start Sentinel (= 0xb)
FS = Field Separator (= 0xd)
ES = End Sentinel (= 0xf)
FC = Format Code  (2 digits)
LRC= Longitudinal Redundancy Check

******************************************************************************

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