Format: nLength: 6Fixed length
DE 73
Date, Action
What it is
YYMMDD on which a requested action (e.g. file update) is to occur.
Specification reference
Defined in ISO 8583:1987 (base). Card networks publish their own dialect tables (Visa BASE I / V.I.P., Mastercard CIS) that refine formats, lengths, and — for private-use elements — the entire layout. Always confirm against the interface specification you implement.