9F78

Unprotected Data Envelope 4 is the fourth member of the same Kernel 2 unprotected-envelope family, sharing the identical free-read, non-integrity-protected design already established for 9F75, 9F76, 9F77, and 9F79 throughout this dictionary, and relating, like 9F77, back to 9F75 rather than to multiple neighbours in the sequence. Rather than repeat the same design rationale a fifth time, what's worth noting about this particular slot is structural: a terminal or analysis tool building generic support for this envelope family should treat all five members as a homogeneous group governed by the same trust rules, iterating over whichever of 9F75 through 9F79 a given card actually populates, rather than hardcoding assumptions about which specific numbers a card will use - cards are free to populate any subset of the family depending on what the issuer or scheme actually needs. See EMV Contactless Book C-2.