ISO 8583 · Data fields

Field 34Primary Account Number, Extended

pyiso8583 starter profilesIndependent explanation

What this field describes

The starter profiles assign field 34 to primary account number, extended. The profile comparison below describes its outer container.

The library does not supply a complete list of allowed values or every internal component. Confirm those details in the specification for the connection you are implementing.

Compare the two profiles

Container settings from the pinned pyiso8583 source.
Settingdefaultdefault_ascii
Value encodingASCIIASCII
Length limitUp to 28 bytesUp to 28 bytes
Prefix2 ASCII bytes2 ASCII bytes

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

Length prefix2 bytesASCII length
Field 34≤ 28 bytesASCII value

Read the 2 prefix bytes first, then read that many value bytes. Reject a length that exceeds 28 or the bytes remaining in the message.

Find it in the bitmap

Bitmap
Primary
Position
34
Byte
5
Bit in byte
2

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.