TLV is a data storage method used to make the fast parsing of data easier.
For example, in a transaction initiated from a POS, the use of the TLV structure to read data from the card's chip and to carry that data throughout the authorization process is one such example.
The phrase Tag-Length-Value is commonly abbreviated as TLV.
Tag : What type of data this is (e.g. Application Label, Application Identifier)
Length : The length of the data
Value : The content of the data
For example, below is an example of Field 55 in an ISO-8583 message. The tag-based parsed version is shown underneath:
01495F2A0201245F34010182021C008407A0000000031010950580000000009A031102249B026 8009C01009F02060000000000009F03060000000000009F0607A00000000310109F0802008C9F0 902008C9F100706010A039000009F1A0201249F2608423158936ED6C38F9F2701809F3303E0B0 C89F34034103029F3501229F360200019F3704ACAC66E89F5800DF0100DF0200DF0400
| 5F2A Transaction Currency Code | 124 |
| 5F34 Application Primary Account Number (PAN) Sequence Number | 1 |
| 82 Application Interchange Profile | 1C00 |
| 84 Dedicated File (DF) Name | A0000000031010 |
| 95 Terminal Verification Results | 8000000000 |
| 9A Transaction Date | 110224 |
| 9B Transaction Status Information | 6800 |
| 9C Transaction Type | 0 |
| 9F02 Amount, Authorised (Numeric) | 0 |
| 9F03 Amount, Other (Numeric) | 0 |
| 9F06 Application Identifier (AID) – terminal | A0000000031010 |
| 9F08 Application Version Number | 008C |
| 9F09 Application Version Number | 008C |
| 9F10 Issuer Application Data | 06010A03900000 |
| 9F1A Terminal Country Code | 124 |
| 9F26 Application Cryptogram | 423158936ED6C38F |
| 9F27 Cryptogram Information Data | 80 |
| 9F33 Terminal Capabilities | E0B0C8 |
| 9F34 Cardholder Verification Method (CVM) Results | 410302 |
| 9F35 Terminal Type | 22 |
| 9F36 Application Transaction Counter (ATC) | 1 |
| 9F37 Unpredictable Number | ACAC66E8 |
| 9F58 Unknown tag | . |
| DF01 Unknown tag | . |
| DF02 Unknown tag | . |
| DF04 Unknown tag | . |
