I've had to do some EDI in the Automotive world and Financial world (ACH and Wires) Maybe I've been lucky in my travels, but none of them were terribly difficu

I've had to do some EDI in the Automotive world and Financial world (ACH and Wires) Maybe I've been lucky in my travels, but none of them were terribly difficult, so long as you had a spec doc in front of you. (As a C# Dev, I'd usually use some form of FileHelpers alongside of MultiRecordEngine, if you're having to deal with things like 'correction' records, treat the resulting records as an eventstream and use those to build the final dataset.) What gets -nasty- is when companies violate a spec in a subtle way. In one case, the 'response' file for ACH transfers from one bank 'reused' the leftmost digit in a certain field for their own code. This however made it extraordinarily difficult to reconcile to the original check due to the relative shortness of this identifier.