ISO 8583 · Data fields

Field 65Bitmap, Extended

pyiso8583 starter profilesIndependent explanation

What this field describes

The starter profile labels field 65 Bitmap Extended and allocates sixteen ASCII bytes.

A field definition alone does not establish support for additional field numbers. Check the encoder’s supported range before treating this as a tertiary bitmap.

Compare the two profiles

Container settings from the pinned pyiso8583 source.
Setting	`default`	`default_ascii`
Value encoding	Binary	ASCII
Length limit	Exactly 8 bytes	Exactly 16 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 6516 bytesASCII value

Read exactly 16 value bytes. The next field begins immediately afterwards under this profile; no length prefix belongs to this field.

Find it in the bitmap

Bitmap: Secondary
Position: 1
Byte: 1
Bit in byte: 1

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.