A retailer hands you a routing guide, an EDI mandate, and a go-live date. We scope what compliance will actually cost before you commit to it, then hold the vendor to that scope.
Most brands budget for the software and are surprised by everything else. The document set is the smallest part. Each trading partner needs its own mapping, its own test cycle, and its own set of exceptions once volume starts moving. A single retailer onboarding typically runs six to twelve weeks.
The 850 is the purchase order, the 810 is your invoice, and the 856 is the advance ship notice. The 856 is where most chargebacks originate, because it has to be transmitted before the shipment arrives and has to match the cartons exactly. Getting that one right removes a large share of deductions before they happen.