Before pickup
Use the PO to locate the customer order; create a unique BOL reference for your document.
Freight identifiers
BOL number vs. PRO, SCAC, and PO number
Four numbers can appear on one freight shipment, but they answer four different questions: which document, which carrier shipment, which carrier, and which customer order?
The short answer
A BOL number identifies the shipper’s document. A PRO number identifies the carrier’s shipment record. A SCAC identifies the carrier organization. A PO number identifies the buyer’s order. Keep them separate so the dock, customer-service team, and accounting team can all find the same shipment in their own systems.
Which identifier belongs to what?
| Identifier | Assigned by | Identifies | Usually known | Not the same as |
|---|---|---|---|---|
| BOL number | Shipper or document preparer | The shipper’s freight document or shipment record | Before tendering | It is not the carrier’s tracking number or carrier identity. |
| PRO number | Carrier | The carrier’s shipment-control or tracking reference | At or around pickup, depending on carrier | It is not a standardized federal ID and is not assigned by the shipper. |
| SCAC | NMFTA | A transportation company | Before the shipment; the code belongs to the carrier | It is not a PRO number, USDOT number, MC number, authority, or safety rating. |
| PO number | Buyer or purchasing system | The commercial order | Before the shipment | It is not a freight document or a carrier identifier. |
A simple handoff workflow
At tender
Enter the carrier name and SCAC when the workflow asks for a carrier identifier.
At pickup
Add the PRO number only after the carrier provides it.
After delivery
Use the BOL and PRO together to reconcile customer, carrier, freight-bill, and delivery records.
Freight references — FAQ
Can a BOL number and PRO number be the same?
They can look similar in a particular workflow, but they represent different owners: the shipper controls its BOL reference, while the carrier assigns the PRO. Keep both when both are available so each party can reconcile the same shipment.
Is a SCAC required on every bill of lading?
Do not treat SCAC as a universal federal field requirement. It is an industry carrier identifier that can be requested by a carrier, shipper, receiver, contract, or electronic workflow.
Where does the PO number go?
Use the customer, consignee, or carrier’s requested reference field. A PO links the freight to the purchase transaction; it does not replace a BOL or carrier tracking reference.
Keep the document itself accurate
Sources & scope
Updated August 22, 2026. Scope: U.S. freight terminology. Carrier formats and trading-partner fields can vary.
- NMFTA — what is a SCAC? — official carrier-identifier definition
- UPS glossary — PRO number — carrier-assigned tracking example
- FMCSA operating-authority FAQ — MC-number boundary
Keep your reference—and leave room for the carrier’s
DockBOL prints your BOL reference clearly and supports a carrier PRO number when it is available, so the record follows the shipment across both systems.
Free · no account · scannable BOL and PRO fields