# Container Glossary

Source: https://contsize.com/container-glossary/ · CC BY 4.0 · checked 2026-10-19

The vocabulary of container shipping in plain English: TEU, FEU, tare, payload, VGM, high cube, reefer, OOG, demurrage, detention and 36 more terms — each defined in two sentences with links to the full guides.

- **[BIC code](https://contsize.com/glossary/bic-code/)**: The four-letter owner prefix at the start of a container number — three letters registered with the Bureau International des Containers and the equipment category letter, U for a freight container. It names the company that owns the box, which is often a leasing company rather than the line carrying your cargo; all 85 prefixes we curate are on BIC’s register, read for each code. Look one up with the [container tracking checker](https://contsize.com/container-tracking/).
- **[SCAC](https://contsize.com/glossary/scac/)**: Standard Carrier Alpha Code — a four-letter code identifying a carrier in customs and EDI filings. It is what a bill of lading number starts with: MAEU for Maersk, COSU for COSCO, HLCU for Hapag-Lloyd. A SCAC and a container prefix are entries in two different registers, even where the four letters are the same (MAEU is both): what follows the letters tells them apart, which is why pasting a B/L number into a container field returns nothing.
- **[Bill of lading (B/L)](https://contsize.com/glossary/bill-of-lading/)**: The contract of carriage between shipper and line, and the document that controls release of the cargo. Its number identifies the whole shipment rather than one box, so tracking by B/L shows every container under the booking at once.
- **[House B/L](https://contsize.com/glossary/house-bl/)**: A bill of lading issued by a freight forwarder or [NVOCC](https://contsize.com/container-glossary/#nvocc) to its own customer, sitting underneath the master bill the ocean carrier issued to the forwarder. A house B/L number exists only in the forwarder’s system: no carrier tracker will recognise it, so track with the container number instead.
- **[NVOCC](https://contsize.com/glossary/nvocc/)**: Non-vessel-operating common carrier — a company that sells ocean transport and issues its own bills of lading without owning ships. It buys space from the lines and resells it, which is why an NVOCC shipment is tracked through the NVOCC, not through the carrier whose vessel is actually moving the box.
- **[Booking number](https://contsize.com/glossary/booking-number/)**: The reference for a space reservation with a carrier, issued before the containers are assigned. One booking can cover many boxes. 10 of the 18 carrier trackers we tested accept a booking number; the rest want a container or B/L number instead.
- **[Gate-in](https://contsize.com/glossary/gate-in/)**: The event recorded when a loaded container passes into the terminal ahead of loading. It is usually the first thing a carrier publishes about a shipment, which is why a box booked yesterday has nothing to show yet.
- **[Gate-out](https://contsize.com/glossary/gate-out/)**: The event recorded when a container leaves the terminal on a truck or rail car after discharge. It starts the [detention](https://contsize.com/container-glossary/#detention) clock on returning the box empty.
- **[Free time](https://contsize.com/glossary/free-time/)**: The days a container may sit in the terminal, or stay out of it, before charges begin. Time inside the port is billed as [demurrage](https://contsize.com/container-glossary/#demurrage); time outside it as [detention](https://contsize.com/container-glossary/#detention). Both are measured from tracking events, which is the practical reason to watch them.
- **[Empty return](https://contsize.com/glossary/empty-return/)**: Handing the carrier’s container back to a nominated depot once it is unloaded. It is the last event most trackers publish, and it stops the detention clock.
- **[Transshipment](https://contsize.com/glossary/transshipment/)**: Moving a container from one ship to another at an intermediate port rather than sailing it end to end. It is where tracking most often appears to stall: the box can sit at the hub for days between discharge and the connecting load, with no event in between.
- **[AIS](https://contsize.com/glossary/ais/)**: Automatic Identification System — the transponder every large ship broadcasts, carrying position, course and speed. A carrier showing a live map is usually plotting AIS, which tracks the vessel rather than the container: a standard dry box has no power and no radio of its own.
- **[EDI](https://contsize.com/glossary/edi/)**: Electronic Data Interchange — the standardised messages terminals, carriers and customs exchange. Your tracking events are EDI messages rendered as a timeline, which is why they arrive in steps hours apart rather than continuously.
- **TEU**: Twenty-foot equivalent unit — capacity of one 20 ft container, the industry’s unit of count. Full guide: [What is a TEU?](https://contsize.com/what-is-teu/)
- **[FEU](https://contsize.com/glossary/feu/)**: Forty-foot equivalent unit = 2 TEU. Freight rates quoted “per FEU” apply to one 40 ft container.
- **[Tare weight](https://contsize.com/glossary/tare-weight/)**: The weight of the empty container, painted on the doors: 2,230 kg for a 20 ft, within 2 % on 8 of 18 published sheets, which range 2,080–2,570 kg. Subtract it from max gross to get payload. See the [weight guide](https://contsize.com/shipping-container-weight/).
- **[Max gross](https://contsize.com/glossary/max-gross/)**: The heaviest a loaded container may be — box plus cargo — as its CSC plate states: 30,480 kg on 15 of 16 published 20 ft sheets and 32,500 kg on 12 of 15 for the 40 ft; older 40 ft boxes are rated 30,480 kg.
- **[Payload](https://contsize.com/glossary/payload/)**: Max gross minus tare: the cargo weight a container can take — 28,250 kg for a 20 ft dry box and 28,800 kg for a 40 ft rated 32,500 kg, as most published sheets print them.
- **[VGM](https://contsize.com/glossary/vgm/)**: Verified Gross Mass — the weighed, documented weight of a packed container required by SOLAS before vessel loading.
- **High cube (HC)**: A container 9′6″ (2.896 m) tall instead of the standard 8′6″ (2.591 m), per ISO 668. See [high cube container](https://contsize.com/high-cube-container/).
- **[General purpose (GP)](https://contsize.com/glossary/general-purpose/)**: The standard enclosed dry container — as opposed to reefer, open top or other specials. Also called “dry van”.
- **Reefer**: Refrigerated container whose machine holds −30 °C to +30 °C, some units down to −40 °C, by their makers’ sheets. Smaller inside than a dry box: 67.5 m³ in a 40 ft high cube reefer against 76.4 m³. See [reefer dimensions](https://contsize.com/reefer-container/).
- **Open top**: Container with a removable tarpaulin roof for crane loading. See [open top dimensions](https://contsize.com/open-top-container/).
- **Flat rack**: A container reduced to floor and end walls, for machinery and oversized cargo. See [flat rack dimensions](https://contsize.com/flat-rack-container/).
- **ISO tank**: A liquid tank in a 20 ft frame, most often 25,000 L; the published sheets run 20,000–26,000 L. See [tank container](https://contsize.com/tank-container/).
- **[OOG](https://contsize.com/glossary/oog/)**: Out of gauge — cargo protruding beyond the container envelope (over-height, over-width), typically on flat racks or open tops; priced with extra slots.
- **[Twist-lock](https://contsize.com/glossary/twist-lock/)**: The rotating fitting that locks corner castings to ships, chassis, cranes and other containers.
- **[Corner casting](https://contsize.com/glossary/corner-casting/)**: The steel fitting at each of the eight corners — the only points a container is designed to be lifted, stacked and locked by.
- **[CSC plate](https://contsize.com/glossary/csc-plate/)**: The safety-approval plate riveted to the door: max gross, stacking and racking loads, date of manufacture, approval reference and inspection status under the Container Safety Convention; the tare is marked on the door, not here.
- **ISO 6346**: The marking standard behind container numbers (MSKU 307703 8) and size/type codes (22G1, 45R1), which we read in IS 6928:2001 and BIC’s 2022 code table. See [ISO standards](https://contsize.com/iso-container-standards/) or validate a number in the [tracking checker](https://contsize.com/container-tracking/).
- **ISO 668**: The standard fixing a container’s outside dimensions, tolerances and maximum gross ratings — the reason every box fits every ship. We read it in IS 6566:2001 and ГОСТ Р 53350-2009, the 1995 text with its amendments.
- **[Gooseneck chassis](https://contsize.com/glossary/gooseneck-chassis/)**: A lowered road chassis whose front “neck” drops into a tunnel under 40 ft+ containers, cutting overall height — often required for high cubes.
- **[Pallet-wide](https://contsize.com/glossary/pallet-wide/)**: European container variant 2.420–2.444 m wide inside (the 40 ft is 2.500 m outside), by CMA CGM’s and DP World’s sheets, taking EUR pallets three abreast, or two turned, without waste: CMA CGM’s 45 ft pallet-wide takes 33 EUR pallets in one tier.
- **[One-trip](https://contsize.com/glossary/one-trip/)**: A container that has made one loaded voyage from the factory — “new” for practical purposes in the resale market.
- **[Cargo-worthy (CW)](https://contsize.com/glossary/cargo-worthy/)**: Inspection grade meaning fit for international shipping: structurally sound, valid CSC. Below it sits wind-and-water-tight (WWT), fine for storage.
- **[WWT](https://contsize.com/glossary/wwt/)**: Wind and water tight — keeps weather out but is no longer certified for ocean freight. The usual grade of storage containers.
- **CBM**: Cubic metre — the volume unit of ocean freight. A 20 ft box holds 33.2 m³ (1,172 ft³) inside, per all 18 sheets. See the [CBM guide](https://contsize.com/container-cbm/).
- **[Load line (reefer)](https://contsize.com/glossary/load-line/)**: The red line inside a reefer marking maximum cargo height — air must circulate above the load.
- **[Twenty / forty (equipment slang)](https://contsize.com/glossary/twenty-forty/)**: “A twenty” = a 20 ft container; “a forty” = 40 ft; “a forty-five” = 45 ft. “High cube forty” = 40 ft HC.
- **Conex / sea can**: US and Canadian slang for a shipping container. See [container names](https://contsize.com/conex-box/).
- **[Intermodal](https://contsize.com/glossary/intermodal/)**: Moving between ship, rail and truck without unpacking — the whole point of the standard container.
- **[Demurrage](https://contsize.com/glossary/demurrage/)**: Charges for a container sitting in the port beyond its free days — the terminal’s meter running on your box until you collect it.
- **[Detention](https://contsize.com/glossary/detention/)**: Charges for keeping the carrier’s container outside the port beyond free time — the clock between picking the box up and returning it empty.
- **[LCL / FCL](https://contsize.com/glossary/lcl-fcl/)**: Less-than-container-load vs full-container-load. LCL shares a box with other shippers’ cargo, priced per CBM; FCL books the whole container. A small shipment is usually cheaper as LCL; the volume at which a whole box wins depends on the two rates on your lane — see the [CBM guide](https://contsize.com/container-cbm/).
- **[Dunnage](https://contsize.com/glossary/dunnage/)**: The material that fills voids and braces cargo inside the box — airbags, timber, boards. Its weight counts toward VGM.
- **[Lashing](https://contsize.com/glossary/lashing/)**: Steel rods and turnbuckles securing container stacks to the ship’s deck — the system that keeps stacks several tiers high aboard in a seaway.

Every term you meet on spec sheets, quotes and this site — defined briefly, with links where a full guide exists. All the guides themselves are gathered on the [container guides](https://contsize.com/container-guides/) page.

## Related pages

- [ISO container standardsISO 668 · ISO 6346 · CSC](https://contsize.com/iso-container-standards/)
- [Conex box & container namesCONEX = Container Express · since 1952](https://contsize.com/conex-box/)
- [What is a TEU?Twenty-foot Equivalent Unit](https://contsize.com/what-is-teu/)
- [Shipping container weightTare · Payload · Max gross · VGM](https://contsize.com/shipping-container-weight/)
- [Container FAQThe questions people actually ask](https://contsize.com/container-faq/)