Format: bLength: 8Fixed length
DE 96
Message Security Code
What it is
Security code for network management (e.g. key-exchange) messages.
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.