Format: ansLength: ...999Variable (LLLVAR — 3-digit length prefix)
DE 61
Reserved — Private (POS Data)
What it is
Private use. Visa: POS data (cardholder-present, terminal attendance, etc.). Mastercard: POS data extension.
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.