Field notes
Segment-level explanations of the transaction sets people actually get stuck on, written for whoever is holding a broken file at four in the afternoon. No gated PDFs, no newsletter wall.
A segment-by-segment walkthrough of an ANSI X12 850 purchase order: ISA, GS, ST, BEG, N1 loops, PO1 line items, and the CTT/SE trailers explained in plain English.
What AK3, AK4, and AK5 error codes actually mean in an X12 997 functional acknowledgment, and how to trace a rejection back to the segment that caused it.
How an X12 810 invoice maps to a paper invoice: BIG header, N1 party loops, IT1 line items, TDS totals, and the SAC allowance and charge segments that cause most disputes.
Shipment, order, tare, pack, and item levels in an X12 856 advance ship notice — why HL loops confuse everyone, and how to read the parent-child structure correctly.