Shipping terms glossary: ARO, LTL, RMA, SLI and more

In shipping, ARO means "after receipt of order," so "ships 10 days ARO" means the goods ship 10 days after the seller gets your order. LTL means less-than-truckload freight that shares a trailer with other shippers, RMA is a return merchandise authorization, and an SLI is a shipper's letter of instruction that tells a freight forwarder how to handle an export.

How to use this glossary

Freight paperwork is full of abbreviations, and the same three letters can mean different things to a trucker, a customs broker and a warehouse. This glossary groups the most common terms by theme so you can find related ideas together.

Each entry gives a short, plain-language definition. Where a rule or code depends on the carrier, country or a published tariff, we say so, because the authority that publishes the rule always has the final word.

Order and returns terms

These terms show up on quotes, purchase orders and order confirmations long before anything is loaded on a truck. They set expectations about timing and about what happens when goods come back.

ARO (after receipt of order)

Lead time counted from the day the seller receives and accepts your order. "Ships 2 to 3 weeks ARO" means the clock starts at order receipt, not at payment or at delivery.

RMA (return merchandise authorization)

A number the seller issues before you send goods back. It links the return to the original order, and many sellers refuse packages that arrive without it, so write it where the seller asks (often on the label or packing slip).

Lead time

The total time between placing an order and receiving it, including production and transit.

Backorder

An item that is ordered but not currently in stock, so it ships later than the rest of the order.

Drop ship

The seller has a supplier ship directly to the end customer instead of shipping from its own warehouse.

Freight modes and capacity

The mode you choose affects price, transit time and the paperwork you need. Domestic truck freight in the United States is usually booked as parcel, LTL or full truckload, while international freight often moves by ocean container or air.

LTL (less-than-truckload)

Freight that does not fill a whole trailer, so it shares space with other shippers' pallets. LTL carriers price it using weight, distance and freight class, and the shipment usually passes through terminals before delivery.

FTL (full truckload)

A shipment that uses an entire trailer, or one shipper paying for the whole trailer. It usually moves directly from pickup to delivery with less handling than LTL.

Parcel

Small packages moved by parcel carriers, usually priced by weight, size and zone rather than freight class.

TEU (twenty-foot equivalent unit)

The standard way to count container capacity. One 20-foot container is 1 TEU, and a 40-foot container is 2 TEU.

FCL and LCL (full container load and less-than-container load)

The ocean versions of FTL and LTL. With LCL, your cargo shares a container with other shippers' goods.

Intermodal

A move that uses more than one mode, such as a container that travels by rail and then by truck, without unloading the goods in between.

Reefer

A refrigerated trailer or container that keeps cargo at a set temperature. Food, flowers and some medicines move by reefer, and the shipper usually states the required temperature on the bill of lading.

Drayage

A short truck move of a shipping container, typically between a port or rail ramp and a nearby warehouse. Drayage is often quoted separately from the ocean freight.

Deconsolidation

Unloading a shared LCL container at a container freight station (CFS) and separating each shipper's cargo. Importers of LCL freight often see a deconsolidation or CFS fee on their arrival invoice.

Trucking terms: deadhead, TONU, lumpers and more

Truck drivers, carriers and freight brokers use their own shorthand. These terms often appear on rate confirmations and freight invoices, so shippers see them when an extra charge shows up.

Most of these charges are set by the carrier's tariff or the rate confirmation for the load, not by a government rule. When a fee surprises you, the first place to look is the agreement you or your broker signed.

Rate confirmation (rate con)

The load agreement between a broker and a carrier that states the rate, pickup and delivery appointments, and accessorial terms such as detention, layover and TONU. Most pay disputes come down to what it says.

Deadhead

Miles a truck drives empty, for example from the last delivery to the next pickup. Carriers are not paid for deadhead miles unless the rate covers them, so a remote pickup can cost more.

TONU (truck ordered, not used)

A fee a carrier charges when it dispatched a truck and the load was canceled or not ready. The amount depends on the agreement for that load.

Lumper

A third-party worker or crew hired to load or unload a truck, common at grocery and retail warehouses. Under federal law (49 U.S.C. 14103), a shipper or receiver that requires this help must provide it or pay the costs, and coercing a driver to pay for it is unlawful. Drivers who pay at the dock need the lumper receipt to be reimbursed by their carrier or broker.

Driver detention

Pay a carrier charges when its driver waits at a shipper or receiver beyond the free time in the agreement, often two hours. Free time, the hourly rate and the conditions (on-time arrival, signed in and out times, advance notice) come from the rate confirmation or contract, and free time is commonly counted at each stop separately. This is different from container detention at ports.

Layover

A charge when a driver must wait overnight or longer because a load cannot be picked up or delivered as scheduled.

Chassis

The wheeled steel frame a container sits on when a truck pulls it on the road. Chassis are often rented from equipment pools that bill a daily charge until the chassis is returned.

Liftgate

A powered platform on the back of a truck that lowers freight to the ground. It is an accessorial charge, needed when the delivery site has no loading dock.

Document terms

Most shipments need a small set of documents. The good news is that they share most of the same data, so it pays to enter shipper, consignee and item details once and reuse them. PaperPorter's free bill of lading generator, commercial invoice template and packing list template share one shipment record saved only in your browser.

BOL or B/L (bill of lading)

The document a carrier issues for goods it accepts. It acts as a receipt and as evidence of the contract of carriage, and an order (negotiable) bill of lading can also serve as a document of title. See what is a bill of lading for the full breakdown.

Commercial invoice

The seller's bill to the buyer for an international sale. Customs authorities use it to check the value, description and origin of goods.

Proforma invoice

A preliminary invoice sent before the sale is final, often used for quotes, payment arrangements or import permits.

Packing list

An itemized list of what is in each package, with counts, weights and dimensions. Carriers, customs officers and the receiver use it to check the shipment.

SLI (shipper's letter of instruction)

A document from the exporter to its freight forwarder that gives the details and instructions for an export shipment. In the United States it is often used to authorize the forwarder to file the export information electronically on the exporter's behalf.

Certificate of origin

A statement or certification of the country where goods were produced. Some trade agreements, such as the USMCA, accept a certification with required data elements instead of a fixed form.

Parties to a shipment

Every document names the people and companies involved. Getting these roles right matters, because the carrier delivers to and takes instructions from the parties shown on the bill of lading.

Shipper (consignor)

The party sending the goods, usually the seller or its warehouse.

Consignee

The party the goods are shipped to, who receives them at the destination. On an order bill of lading, the consignee line may read "to order" instead of a name.

Notify party

A company the carrier contacts when the goods arrive, often the buyer or the customs broker.

Freight forwarder

A company that arranges transport on the shipper's behalf, booking carriers and handling documents.

Customs broker

A licensed professional who prepares and files import entries with customs on the importer's behalf.

Bill-to party

Whoever pays the freight charges, which may be the shipper, the consignee or a third party.

Codes and numbers

Freight runs on reference numbers. Each one identifies something different, so a missing or wrong number can delay pickup, billing or customs clearance.

PRO number

A tracking number an LTL carrier assigns to a shipment, used to trace it and to match the freight bill. It often appears as a barcode label on the bill of lading.

SCAC (Standard Carrier Alpha Code)

A unique two-to-four-letter code that identifies a transportation company. It is assigned by the National Motor Freight Traffic Association (NMFTA).

NMFC (National Motor Freight Classification)

A standard published by the NMFTA that groups commodities for LTL pricing. Each commodity has an NMFC item number that points to its freight class.

Freight class

A rating from class 50 to class 500 that reflects how easy or costly an item is to ship, based on factors such as density, handling, stowability and liability. Lower classes are usually cheaper per pound. Check the current NMFC, since classifications are updated.

HS code (Harmonized System code)

An internationally standardized number that classifies traded products. The first 6 digits are shared by participating countries, and countries add more digits for their own tariffs and statistics.

Booking number

The reference an ocean or air carrier gives when it confirms space for your cargo.

Container number

The unique ID painted on each shipping container, four letters followed by seven digits.

Customs and import terms

Imports add a layer of terms that come from customs rules. The examples below are for the United States; other countries have their own filings and names, so check with the customs authority of the destination.

One rule underpins all of them. US Customs and Border Protection (CBP) states that even when you use a broker, the importer of record is ultimately responsible for the correctness of the entry and for all duties, taxes and fees.

Importer of record

The party responsible for making sure imported goods comply with US law and for paying duties. It may be the buyer, the seller under some DDP arrangements, or another party, so confirm who it is before goods ship.

Entry summary (CBP Form 7501) and entry number

The customs declaration filed for an import, showing the importer of record, classification, value and duties. The entry number appears at the top; your broker can supply copies, and you need them to check duties or claim a refund, which generally goes to the importer of record.

HTS code

The US Harmonized Tariff Schedule number, 10 digits built on the 6-digit HS code, that sets the duty rate. The rate applied is generally the one in effect at the time of entry (19 CFR 141.69), not when goods were ordered or shipped.

Customs broker

A person or company licensed under federal law to conduct customs business for others, such as filing entries and paying duties on an importer's behalf. CBP notes that certain importers may file their own entries, so using a broker is common but not always required.

ISF (Importer Security Filing, or "10+2")

Advance cargo information that the importer must give CBP for ocean shipments to the United States, due 24 hours before the cargo is loaded on the vessel at the foreign port. Under the bond conditions in 19 CFR 113.62, liquidated damages of $5,000 can be assessed for each violation.

AMS (Automated Manifest System)

The CBP system carriers use to transmit cargo manifest data. For ocean freight, the carrier must send its cargo declaration 24 hours before the cargo is loaded at the foreign port.

Bonded warehouse

A CBP-supervised facility where imported goods can be stored without paying duty until they are withdrawn. Under 19 CFR 144.5, goods may stay up to 5 years from the date of importation, with extensions possible for good cause.

FTZ (foreign-trade zone)

A secure area under CBP supervision that is generally treated as outside US customs territory for duty purposes. Duty is paid when goods leave the zone for US consumption, and goods exported from the zone are free of duty.

DDP (Delivered Duty Paid)

An Incoterms rule where the seller pays carriage, import clearance and duties to a named destination. The pitfall is that the seller usually chooses the destination agent, and the buyer may still be named as importer or receive a bill before release, so get the details in writing.

Customs exam

A CBP inspection, ranging from an X-ray scan to an intensive exam where the container is unloaded at a centralized examination station. The importer pays the station's charges.

Port and container charges: demurrage and detention

Container charges confuse even experienced importers because two different clocks run at once. Free time, the number of days allowed before charges start, varies by carrier, terminal and contract.

In the United States, the Federal Maritime Commission's billing rule (46 CFR part 541) treats both as fees for using terminal space or containers, including per diem. An invoice must be issued within 30 calendar days from when the charge was last incurred or the billed party does not have to pay it, and the billed party gets at least 30 days to request a waiver or refund.

The FMC also judges these charges by whether they work as an incentive to move cargo (46 CFR 545.5), looking at whether the container was actually available for pickup, whether an empty could be returned, and how government inspections were handled.

Last free day (LFD)

The final day you can collect a container from the terminal before demurrage starts. Ask your forwarder for it in writing for each container, because it depends on discharge date and the carrier's terms, not the vessel's arrival date.

Demurrage

A charge for leaving a loaded container at the port terminal beyond its free time, usually because it has not been picked up or cleared.

Detention

A charge for keeping the carrier's container outside the terminal beyond its free time, for example when an empty container is returned late.

Per diem

A daily charge for equipment, such as a container or chassis, until it is returned. Some carriers use the term in place of detention.

Storage

Fees a warehouse or container freight station charges for holding cargo, separate from the carrier's demurrage.

Telex release

An instruction from the carrier's origin office that the cargo can be released at destination without the paper original bill of lading, usually after the shipper surrenders the originals and origin charges are paid.

Charges and trade terms

The quoted freight rate is rarely the whole bill. Extra services and the trade terms in the sales contract decide who pays what.

Accessorial charges

Fees for services beyond standard dock-to-dock transport, such as liftgate use, residential delivery, inside delivery, limited-access locations or detention (waiting time). Each carrier sets its own list in its tariff.

Fuel surcharge

A variable charge added to the base rate that moves with fuel prices.

Incoterms

Standard trade terms published by the International Chamber of Commerce, currently Incoterms 2020, that define who arranges and pays for carriage, where risk passes and who clears customs. Read what does FOB mean in shipping for a comparison.

Prepaid and collect

Prepaid means the shipper pays the freight charges, while collect means the consignee pays them.

Questions people actually ask about shipping terms

Shippers and new importers tend to run into the same surprises. Here are short answers to the questions that come up most, with the honest caveat that contracts and tariffs often decide the details.

• Customs held my container for inspection. Who pays the demurrage and exam fees? Usually the importer. CBP states that the importer bears the cost of cargo exams, and carriers may still bill demurrage, though the FMC considers how inspections were handled when it reviews such charges.
• Can the warehouse keep my goods if I do not pay the charges? Carriers and warehouses commonly hold cargo until charges are paid, and their terms often give them a lien. Paying under protest and then disputing the bill is often cheaper than letting storage grow.
• Are customs clearance and handling fees legitimate? Brokers and forwarders do charge for preparing entries and arranging release. Ask for a full quote of destination charges before the goods ship so nothing arrives as a surprise.
• Why is my cargo stuck even though I paid the supplier? The carrier may need the original bill of lading or a telex release, and the origin office may wait until origin charges are settled. Ask your supplier to confirm the release before the vessel arrives.
• What is the difference between driver detention and container detention? Driver detention pays a trucking company for waiting time at a dock. Container detention is a carrier charge for keeping its container too long. One shipment can incur both.
• Who pays the lumper? Under 49 U.S.C. 14103, a shipper or receiver that requires loading or unloading help must provide it or cover the cost. In practice, drivers are often asked to pay first and get reimbursed, so keep the receipt.
• What does freight prepaid on the bill of lading cover? It means the main freight was paid at origin. It does not automatically cover destination terminal charges, customs fees or duties.
• What does a carrier need to get paid detention? Terms agreed in writing before loading, arrival on time for the appointment, in and out times on the bill of lading, and a message to the broker or facility once free time runs out. Claims are mostly lost over arrival time, not the rate, so timestamped records matter.
• A broker will not pay what the rate confirmation says. What can a carrier do? Escalate in writing with the rate confirmation and proof of delivery. Federal rules require property brokers to keep a $75,000 surety bond or trust fund (49 CFR 387.307), which carriers can claim against when a broker fails to pay.
• Do I owe demurrage if the terminal was closed or held my container? Possibly not. The FMC weighs whether the container was available for pickup, so collect terminal timestamps and dispute the invoice with the carrier. An FMC complaint is an option if the carrier will not budge.
• I paid DDP or used a courier. Am I the importer of record? Not necessarily. Check the importer of record field on the entry summary. If another company is named, any refund of duty goes to that company first.

Common mistakes with shipping terms

Small vocabulary mix-ups cause real costs. These are the ones carriers, brokers and warehouses see most.

• Putting a PO number in the PRO number field: the carrier cannot trace or bill the shipment correctly.
• Guessing the freight class: if the carrier inspects the freight and finds a different class or weight, it can reclassify the shipment and bill the difference.
• Forgetting accessorials at booking: residential delivery, liftgate or limited-access sites that were not on the bill of lading are often billed later at a higher rate.
• Filing the ISF late: it is due 24 hours before loading at the foreign port, not when the vessel arrives.
• Assuming DDP means no paperwork for you: if you are named as importer, you may still be responsible for the entry.
• Letting free time run out: arranging the customs broker and the drayage truck after the vessel arrives is a common way to rack up demurrage.
• Listing the forwarder as consignee by mistake: the carrier delivers to and takes instructions from the parties on the bill of lading.
• Leaving the dock without signed in and out times: once the truck pulls out, proving detention gets much harder.
• Pulling every container the day it is available: each pulled box starts its own detention clock, so time pickups to how fast your warehouse can unload.

Turning terms into correct paperwork

Knowing the vocabulary is half the job. The other half is putting the right value in the right box, and making sure each party is named in the right role.

Before you print, compare your bill of lading, commercial invoice and packing list. Piece counts, weights, parties and descriptions should match across all three, because differences are a frequent reason for customs questions and billing disputes.

If you need to share or archive the finished documents, our free PDF tools can help. They run in the browser, so nothing is uploaded.

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Last updated 2026-10-05. General information, not legal or customs advice. Check current rules with the relevant agency or carrier.

Frequently asked questions

What does ARO mean in shipping?

ARO stands for "after receipt of order." A lead time such as "ships 10 days ARO" means the goods ship 10 days after the seller receives your order.

What does LTL mean in shipping?

LTL means less-than-truckload. It is freight that does not need a full trailer, so it shares space with other shippers' goods and is priced by weight, distance and freight class.

What does RMA mean in shipping?

RMA stands for return merchandise authorization. It is a number the seller gives you before you return goods so the return can be matched to your order.

What is the difference between demurrage and detention?

Demurrage is charged when a loaded container stays at the port terminal past its free time. Detention is charged when the carrier's container is kept outside the terminal past its free time.

What is a lumper fee?

A lumper fee pays third-party workers who load or unload a truck. Under federal law, a shipper or receiver that requires this help must provide it or cover the cost.

How do I find my freight class?

Freight class comes from the commodity's NMFC item, which is published by the National Motor Freight Traffic Association. Many carriers will help you confirm it, and using the wrong class can lead to a reclassification charge.