Discover D-PAS — EMVCo Kernel 6
Discover D-PAS (Kernel 6): its own TTQ (9F66) layout with Fast Mode and Transit-profile bits, plus Data Storage and tearing-recovery handling.
Overview
Kernel 6 is the EMVCo contactless kernel for Discover D-PAS (also used for Diners Club). It uses a Terminal Transaction Qualifiers (9F66) object, but with its own bit layout distinct from Visa.
Notable Kernel 6 additions are a Fast Mode and a Transit-terminal profile (byte 2), a Consumer Device CVM for Transit MCC bit (byte 3), and support for Data Storage with tearing-recovery handling for interrupted taps.
Transaction flow
Discover D-PAS (Kernel 6). Kernel 6 uses its own TTQ (9F66) layout, supports a Fast Mode and Transit profile, and offers Data Storage with tearing-recovery handling.
1App Selection
PPSE → AID · format checks
Entry Point selects the Discover application; the kernel runs format-analysis and PDOL checks before processing.
TTQ (9F66) — Discover layout
Byte 1 carries mag-stripe / EMV-mode / EMV-contact-chip / offline-only / online-PIN / signature bits; byte 2 adds Fast Mode and Transit-terminal selection; byte 3 adds Issuer Update and Consumer Device CVM (including for transit MCC).
Decode it live: TTQ Decoder (Discover)
Cardholder verification
CVM uses the TTQ CVM-required and consumer-device-CVM bits, including the dedicated Consumer Device CVM for transit MCC.
Key data elements
| Tag | Name | Notes |
|---|---|---|
9F66 | Terminal Transaction Qualifiers (TTQ) | Discover D-PAS layout (own bit map). |
BF11 | Write Data Storage Template | Kernel 6 data storage. |