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             AUTOMATIC TRANSACTION MAGNETIC STRIPE FORMAT
             --------------------------------------------
                     ANSI X4.16 (1976)  ISO 3554
                        

   -------------------------------------------------  <-- top edge of card
                                        .223"
   -------------------------------------------------  <-----
   TRACK 1      IATA                    .110"           |
   -------------------------------------------------       |
   TRACK 2      ABA                     .110"         mag stripe
   -------------------------------------------------    |
   TRACK 3      THRIFT                  .110"           |
   -------------------------------------------------  <-----

TRACK 1: developed by the International Air Transportation Assoc. (IATA),
         contains alphanumeric info for automation of airline ticketing
         or other reservation database applications.

TRACK 2: developed by the American Bankers Assoc. (ABA), contains numeric
         info for automation of financial transactions.
         This track is also used by most systems which require an 
         identification number and a minimum of other control info.

TRACK 3: developed by the Thrift Industry, contains info, some of which
         is intended to be changed (re-recorded) with each transaction,
         e.g. cash dispensers which can operate "offline".


            density in bits     char length in bits     info content
                per inch        including parity bit
            ---------------     --------------------    ------------ 

TRACK 1:         210                    7          79 alphanumeric chars
TRACK 2:          75                    5          40 numeric chars
TRACK 3:         210                    5         107 numeric chars


Information is read right to left beginning with the Start Sentinel
(SS) character located at the right edge of the card.

TRACK 1:

LRC | ES | DISCRETIONARY DATA | FS | NAME (26 char max.) | SS
(coded char set: 6 bit subset of ASCII plus parity)             

TRACK 2:

LRC | ES | DISCRETIONARY DATA | FS | ACCOUNT NUMBER | SS
(coded char set: BCD 4 bit subset plus parity)

TRACK3:

LRC | ES | DISCRET. DATA | AS | USE AND SECURITY DATA | FS | ACCOUNT #
 | SS (coded char set: BCD 4 bit subset plus parity)


SS      Start Sentinel
FS      Field Separator
AS      Account Separator
ES      End Sentinel
LRC     Longitudinal Redundancy Check

For error detection an odd parity bit is included in each character
and a longitudinal redundancy check (LRC) character is encoded after
the End Sentinel (ES).

