9F73

Protected Data Envelope 4 completes the numbered set of protected envelopes covered in this dictionary alongside 9F71, 9F72, and 9F74, all sharing the identical write-access-protected, freely-readable design that distinguishes the protected family from its unprotected counterparts (9F75 through 9F79). With all four protected envelopes and five unprotected ones now documented, the pattern worth carrying forward is structural rather than per-tag: Kernel 2's data-storage feature offers a fixed menu of lightweight, numbered fields split by write-access policy, and any given card populates whichever subset its issuer or scheme actually needs - a terminal or analysis tool's job is to read whichever envelopes are present and hand their contents to whatever scheme-specific logic knows how to interpret them, not to expect a fixed, universal content model across all nine envelope tags. See EMV Contactless Book C-2.