Amount, Transaction
What it is
Transaction amount in the transaction currency (DE 49), right-justified, zero-padded, in minor units.
The amount is expressed in the minor unit of the currency in DE 49 — no decimal point. 000000012345 with currency 840 (USD, exponent 2) is $123.45; with 392 (JPY, exponent 0) the same digits are ¥12,345.
For partial approvals and incremental authorizations the amount in later messages differs from the original; DE 95 (replacement amounts) and DE 54 (additional amounts) qualify it. Dynamic currency conversion pairs DE 4/49 (transaction) with DE 6/51 (cardholder billing).
Example values
000000012345123.45 in a 2-exponent currency such as USD or EUR.DE 4 on the wire
Bitmap position
DE 4 is bit 4 of the primary bitmap: byte 1, mask 0x10. A primary bitmap with only DE 4 present reads 1000000000000000 in hex.
Length
DE 4 is fixed length: always 12 digits, with no length prefix. A parser reads exactly that many and moves on, so shorter values are right-aligned and padded with leading zeros.
Size in the message
At most 12 bytes when the message travels as text (ASCII or EBCDIC), or 6 bytes in binary dialects that pack digits as BCD.
Format n
Format n means numeric: the digits 0–9 only.
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.