spec.md

	Field Name	Description	Length	Encoding	Request/Response	Example Value
0	MTI	Message Type Indicator	4 Fixed	BCD	Both	0100 / 0110
1	Bitmap	Bitmap indicating presence of data elements	8 Fixed	Binary	Both	7FFFFFFFFFFF0000
2	Primary Account Number (PAN)	The cardholder's account number	Up to 19 Variable (LL)	BCD	Request	1234567890123456
3	Amount	Transaction amount in the smallest currency unit. The value is right justified with leading zeroes.	6 Fixed	BCD	Both	000100 (for 1.00)
4	Transmission Date & Time	The date and time the message was sent	20 Fixed	BCD	Both	20230810123456
5	Approval Code	Code for approving the transaction	2 Fixed	BCD	Response	00
6	Authorization Code	Code for authorizing the transaction	6 Fixed	BCD	Response	123456
7	Currency	Transaction currency code	3 Fixed	BCD	Both	840 (for USD)
8	Card Verification Value (CVV)	Card security code	4 Fixed	BCD	Request	1234
9	Card Expiration Date	The card's expiration date	4 Fixed	BCD	Request	2512
10	Acceptor Information	Composite field with details about the acceptor/merchant	Up to 999 Variable (LLL)	ASCII	Request	(See Below)
11	STAN	Systems Trace Audit Number, a unique identifier for the transaction	6 Fixed	BCD	Both	654321