Tick the data elements to build a bitmap, or paste one to see which fields it turns on. The hex,
the binary and the field list all describe the same bitmap and stay in sync as you edit any of them.
Bit 1 is set for you whenever a field of 65 or above is on. Nothing is sent anywhere.
16 hex characters, or 32 when a secondary bitmap is present.
Comma or space separated. DE 55 and F55 both read as 55.
64 bits, or 128 with a secondary bitmap. Grouping spaces are ignored.
0
Fields on
8
Bitmap bytes
No
Secondary bitmap
Could not read
Worth knowing
Primary bitmap — bits 1 to 64
Names from the built-in ISO 8583:1987 field table
Secondary bitmap — bits 65 to 128
Selected fields
No fields selected yet.
How the bitmap works
The bitmap is a run of 8 bytes that follows the MTI. Read left to right, bit 1 is the most
significant bit of the first byte and bit 64 the least significant bit of the eighth. A bit
that is set means the matching data element is present in the message, in ascending order.
Bit 1 is the exception: it does not stand for a field. It says that a second 8-byte bitmap
follows immediately, carrying bits 65 to 128. That is why turning on any field from 65 up
here sets bit 1 and widens the hex to 32 characters.
Field names come from the built-in ISO 8583:1987 table. Acquirers routinely reassign the
private-use bits, so check the names against your own spec — the
config builder
holds a custom table, and the
decoder
uses it to frame a whole message.