9F1D

Terminal Risk Management Data is one of the few EMV tags whose internal structure is explicitly not defined by the core specification - its layout is proprietary to the terminal manufacturer or the payment scheme deploying it, used to steer risk-management checks beyond what the standard fields, like the related TVR (tag 95), already cover. Because there's no universal way to decode it, a terminal or acquirer integrating a new scheme's risk logic has to consult that scheme's own documentation for what 9F1D actually contains, rather than assuming EMV Book 3 alone describes it. In practice this makes it one of the more opaque fields to debug from a generic EMV toolkit: a decoder without scheme-specific knowledge can report that 9F1D is present and how long it is, but can't meaningfully interpret its bytes the way it can for a standard bitmap tag like the TVR. A card or terminal pair from different schemes disagreeing about what 9F1D should contain is a scheme-configuration mismatch, not a spec-compliance bug in the ordinary sense. See EMV 4.4 Book 3.