So I understand and realise that ISO8583 messages are different from spec to spec but I'm wondering if there's a resource somewhere that can help me determine which fields are an absolute must. An '0200' message for example must surely have the PAN and Amount fields?
I'm finding it difficult to locate any such resource and it would be fantastic to have a look at some generic templates even if they carry additional info.
Any help is very much appreciated.
I can confirm that the implementation of ISO8583-like specifications will be different due to different customized requirements.
Answering to your questions about 0200 Financial message in ISO8583:1987(like) version, below the approximate list of required Data Elements (DE):
- MTI: Message Type ID - sure Must have.
- DE000: Primary bitmap - Must have because mandatory fields in the Primary bitmap set.
- DE002: PAN data - will be mandatory in case Manual PAN entry (or E-Com) and sometime duplicate PAN from Card Track or Chip
- DE003: Processing code - must have to determine transaction type
- DE004: Amount - required for financial Transaction request. For Balance request can be 0 or absent.
- DE011: STAN System Trace Number - required to track transactions messages
- DE012 and DE013: Local transaction date and time
- DE014: Date, expiry - required for Manual PAN entry
- DE022: POS entry mode - mandatory to determine Terminal profile
- DE035: Track 2 Data - mandatory in case read Megnetic Swipe
- DE041: Terminal Identifier - the minimum required to determine merchant Point of Service (Sale)
- DE049: Currency code, transaction - usually used. Local markets may skip this field and determine currency at the host side.
- DE052: PIN block, encoded - mandatory in case Online PIN used for authentication.
- DE055: ICC data - Mandatory in case Contact or Contactless(EMV) card used
The rest is optional or can be used depending of conditions.