ISO 8583 · Data fields

Field 37Retrieval Reference Number

pyiso8583 starter profilesIndependent explanation

What this field describes

The retrieval reference number uses a fixed twelve byte container in both starter profiles.

Keep it with the related transaction identifiers. Its presence alone does not prove authorization, settlement or a bank deposit.

Compare the two profiles

Container settings from the pinned pyiso8583 source.
Setting	`default`	`default_ascii`
Value encoding	ASCII	ASCII
Length limit	Exactly 12 bytes	Exactly 12 bytes
Prefix	None	None

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 3712 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: 37
Byte: 5
Bit in byte: 5

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.