Crates arrive on a Friday afternoon. Working through the installation checklist, the engineer opens the packing list. What is the engineer reconciling it against, and why is that the checklist's first hardware step?

The installation checklist opens with a reconciliation between the order's bill of materials and the delivered packing list, because every later step assumes the crates contain what the design assumed: the head unit, each expansion shelf, rail kits matching the rack type, cables, optics and any option cards. Performing the reconciliation at receipt time means a shortfall becomes a vendor action while the shipment is still evidence and inside claim windows, instead of an installation-day emergency. Starting from the customer's asset register fails as a first step because the register reflects what the site already owns, not what this order should contain—the bill of materials is the definition of the expected shipment. Reconciling against the invoice fails by concept because a financial document and a configuration document answer different questions; an item can be paid for and still be absent from the crate. Using the rack elevation instead fails because elevations show placement and clearances, not a complete parts list with quantities. Exam caveat: items the customer sources separately, such as third-party rails or facility cables, legitimately fall outside the vendor's packing list and need their own tracking. Operational check: tick each bill-of-materials line against the packing list item by item, photograph carton labels, and file any mismatch with the vendor the same day.