9F4F
Log FormatLog Format is the tag-and-length list that describes the layout of each entry in the transaction log the Log Entry tag (9F4D, covered earlier) points to - the same request-list mechanism as the PDOL, CDOLs, and other DOLs already covered throughout this dictionary, but describing a data structure to be read rather than data to be supplied to a command. Without 9F4F, a reader that has located the log via 9F4D still wouldn't know how to parse any individual record it retrieves - the log's raw bytes are meaningless without knowing which tags, in which order, each entry actually packs. Because log content and layout are both card-defined rather than EMV-mandated in any fixed sense, two cards' transaction logs can have completely different structures even if both support the log-reading feature, which is exactly why 9F4F has to be read fresh for each card rather than assumed from a previous one. See EMV 4.4 Book 3.
Interactive decoder
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Binary (6): 9F27019F3602
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Decoded example
Example value: 9F27019F3602
Related tags
Properties
| Tag | 9F4F |
|---|---|
| Name | Log Format |
| Format | Binary |
| Length | variable |
| Source | Card (ICC) |
| Templates | — |
| Books | EMV 4.4 Book 3 |
Frequently asked questions
- What is EMV tag 9F4F?
- Log Format is the tag-and-length list that describes the layout of each entry in the transaction log the Log Entry tag (9F4D, covered earlier) points to - the same request-list mechanism as the PDOL, CDOLs, and other DOLs already covered throughout this dictionary, but describing a data structure to be read rather than data to be supplied to a command. Without 9F4F, a reader that has located the log via 9F4D still wouldn't know how to parse any individual record it retrieves - the log's raw bytes are meaningless without knowing which tags, in which order, each entry actually packs. Because log content and layout are both card-defined rather than EMV-mandated in any fixed sense, two cards' transaction logs can have completely different structures even if both support the log-reading feature, which is exactly why 9F4F has to be read fresh for each card rather than assumed from a previous one. See EMV 4.4 Book 3.
- What format and length does EMV tag 9F4F use?
- Tag 9F4F uses the Binary format and is normally variable long.
- Is tag 9F4F provided by the card or the terminal?
- Tag 9F4F (Log Format) is provided by the Card (ICC).
Sources
- EMV_v4.4_Book_3_Application_Specification, p. 151
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