ISO 8583 · Data fields

Field 4Amount, Transaction

pyiso8583 starter profilesIndependent explanation

What this field describes

This is the transaction amount container. Both starter profiles use twelve ASCII bytes without a length prefix.

The bytes alone do not carry a decimal separator or currency interpretation. Read the transaction currency and the connection’s amount scaling rules together.

Compare the two profiles

Container settings from the pinned pyiso8583 source.
Settingdefaultdefault_ascii
Value encodingASCIIASCII
Length limitExactly 12 bytesExactly 12 bytes
PrefixNoneNone

Length limits describe encoded values. They exclude any length prefix. The profiles can be customized; these settings do not establish the required fields or accepted values for a live connection.

Read the field boundary

Field 412 bytesASCII value

Read exactly 12 value bytes. The next field begins immediately afterwards under this profile; no length prefix belongs to this field.

Find it in the bitmap

Bitmap
Primary
Position
4
Byte
1
Bit in byte
4

Positions start at one. Bits are counted from the most significant bit of each bitmap byte. This calculation locates the field’s presence indicator, not its value.