Study the CDGP domain by re-shipping one product three ways. Take a single item, classify it under the UN framework, then determine its proper shipping name, packaging, marking, documentation, and quantity limits separately for air, sea, and ground transport. Where the modes diverge is where your learning effort belongs. The comparison table, worked scenarios, and four-week sequence below turn that principle into a concrete, checkable plan.
Why one shipment answers to different rulebooks
Dangerous goods rules share a UN Model Regulations backbone, but air, sea, and ground transport each apply their own derived requirements. A shipment that is compliant by sea can be non-compliant by air without changing the product itself.
Trace this example: a consignment of flammable liquid in a single drum travels to the port by truck, crosses the ocean, and continues by air to the final destination. If you planned the shipment once using sea-transport rules, the truck leg and air leg may each need different packaging, documents, and quantity treatment. The classification rarely changes across modes, but nearly everything downstream can.
Worked scenario: a shipper labels drums of paint thinner for ocean transport, then reoffers the same drums to a freight forwarder for an air charter without rechecking requirements. The better decision is to treat the air offer as a new shipment: re-verify the proper shipping name, packing instruction, and quantity limits for air, and re-document accordingly. The mode change resets the compliance analysis, and recognizing that reset is the habit to build before the exam.
- In your notes, keep a three-column log for every product you study: identical across modes, stricter in this mode, absent in that mode.
- This log trains the regime-switching habit directly and gives you a revision artifact you can rebuild from memory later.
Classification: distinguishing hazard class from packing group
Classification answers two separate questions. The hazard class describes the danger the article or substance presents. The packing group, used for certain classes, grades how dangerous that substance is within its class.
Classes such as flammable liquids, flammable solids, oxidizers, toxic substances, and corrosives each describe a kind of danger. Packing groups I, II, and III rank severity for classes where severity varies, with I the greatest degree of danger. A corrosive and a flammable liquid can share a packing group while belonging to different classes, so never derive one from the other. Also learn the concept of substances presenting multiple dangers, where classification may need to consider the most stringent applicable requirement.
Worked scenario: a technician assigns a flammable liquid to Packing Group III because its hazard class seems mild, using a rule of thumb rather than the substance's properties. The better decision is to determine the packing group from the relevant classification criteria for that class, such as flash point and boiling point behavior in a labeled worked example, and to check whether test data or a competent-authority determination already exists. Guessing severity within a class can cascade into the wrong packaging, label, and documentation, so the tracing method drills which criterion drives the assignment until the reasoning is automatic.
- Self-check: for each of Classes 3, 4, 5, 6.1, and 8, write one sentence stating whether a packing group applies and what property distinguishes the groups.
- If any sentence is vague, that is your next study target.
UN numbers and proper shipping names: choosing the right entry
Every dangerous goods shipment is described by a UN number and a proper shipping name drawn from the dangerous goods list, sometimes with modifiers such as n.o.s. entries when no specific name fits.
The proper shipping name is the core of the transport description, and it must be selected from the appropriate list entry, not invented from marketing names. Generic n.o.s. entries exist for mixtures that lack a specific entry, but using one when a specific entry applies is a selection error. Learn how the alphabetical order of descriptive text works in list entries, and how technical names must accompany n.o.s. entries.
Worked scenario: a shipper describes a commercial mixture containing flammable acetone as a generic flammable liquid, n.o.s., because the mixture's trade name is unfamiliar. The better decision is to check whether a component's specific entry governs the description; if a generic entry is genuinely required, the technical name of the hazardous component must be added to the description. The difference matters because the transport description drives downstream requirements, and an incorrect entry can mislead every handler in the chain. Practice by drafting full transport descriptions, UN number plus proper shipping name plus class, for five different products, and have the entries checked against the lists.
- Keep a small reference card of the structure of a transport description rather than memorizing entries.
- Knowing how to read the list is the transferable skill.
Packaging, marking, and labeling: reading instructions rather than guessing
Packaging requirements flow from the list entry and its referenced packing instruction, and UN specification packaging must match the marks on its packaging. Overpacks add their own marking and labeling duties.
Packing instructions are written to be read, not memorized: they specify allowed packaging types, closure and inner-packaging limits, and, for some modes, quantity limits per package. The UN specification mark on a drum or box encodes the design type and performance level, and the packaging used must satisfy the instruction and match the substance's requirements. Overpacking compliant packages does not remove the inner packages' marks and labels; it adds requirements for the overpack itself.
Worked scenario: a warehouse consolidates several compliant boxes of a flammable liquid into a stretch-wrapped pallet and removes the visible labels because they are now on inner boxes hidden by wrap. The better decision is to treat the pallet as an overpack where applicable, keep the inner packages' marks and labels visible or reproduce them on the overpack, and confirm the consolidation does not break any segregation or package-count constraints. The mistake is treating packaging compliance as a one-time event at the carton level. Practice by photographing or sketching a compliant package and an overpack of the same goods, and annotating every required mark, label, and orientation arrow.
- Expected observation from that exercise: the overpack carries duplicates of the required labels plus any overpack marking.
- The specification marks remain the inner packages' responsibility.
Documentation: matching the paper to the mode
Dangerous goods transport requires documents whose form and content differ by mode. The shipper's obligations include accurate descriptions, emergency information where required, and consistency between documents and packages.
For air transport, the shipper's declaration for dangerous goods is the core document with a prescribed format; sea and ground frameworks have their own documentation conventions, and some limited-quantity or excepted shipments may travel on the ordinary transport document with specific notations. The constant across modes is the transport description's content: UN number, proper shipping name, class, packing group where applicable, and quantity. The variable is the form, the certifications, and the supplementary information each regime demands.
Worked scenario: a forwarder copies an air-mode declaration's wording onto a consignment moving only by sea, then wonders why the emergency contact and additional handling information do not align with the sea documentation conventions. The better decision is to rebuild the document set from the sea framework's requirements, keeping the verified transport description but letting each mode's documentation rules dictate form and content. The lesson is that the transport description is portable across modes; the paperwork built around it is not. Drill this by writing the same consignment's documentation summary twice, once per mode, and marking every element that changes.
- Self-check rubric for any document you draft: description complete, quantities consistent with packages, emergency information present where required.
- Signatures and certifications must be correct for the mode.
Quantity concepts: limited, excepted, and fully regulated
Dangerous goods frameworks offer relief pathways for small quantities, but eligibility is mode-specific. A consignment qualifying for a limited-quantity pathway in one regime may be fully regulated in another.
Limited quantity provisions and excepted quantity provisions are distinct concepts: limited quantities generally use the ordinary packaging with quantity caps and specific marking, while excepted quantities involve small amounts in specified combination packaging. Relief pathways typically reduce labeling and documentation, not classification. Critically, these pathways are defined within each modal rulebook, so the same substance at the same size can be eligible by one mode and ineligible by another.
Worked scenario: a shipper who routinely moves small retail packages of a consumer product under a ground limited-quantity pathway fills an air freight container with the same packages, marked for ground relief, without re-checking air eligibility. The better decision is to verify the air framework's treatment of that substance and quantity before tendering, since the relief pathway that applied on the ground may not carry over. The mistake matters because relief pathways only excuse the requirements their own regime defines. Compare the two pathways in a table: packaging basis, quantity caps, marking required, documentation treatment, and mode availability.
- Self-check: given a substance and package size in a labeled practice example, state which pathway applies per mode, or state fully regulated.
- Justify each answer with the eligibility criteria you checked.
A four-week tracing sequence with readiness checks
Prepare by threading five products through three modes across four weeks: classification first, then names, packaging, documents, and quantity pathways, ending with a full self-audit against a rubric.
Week one, classify five varied products and record class, packing group where applicable, and any subsidiary danger considerations. Week two, select proper shipping names and draft transport descriptions, and build the mode-comparison table for each product. Week three, work packaging: read the referenced packing instructions, sketch compliant packages and one overpack, and draft documentation summaries per mode. Week four, work quantity pathways and segregation basics, then re-do all five products from scratch without notes.
Compare this sequence with passive chapter-by-chapter review: chapter review teaches each rulebook in isolation, while the tracing sequence forces you to notice where the rulebooks diverge, and that divergence awareness is the payoff of the method. The table below is your anchor artifact; rebuild it from memory by week four and check it against your references. Treat the readiness checks below as learning milestones, not as passing predictions, and use the free practice questions and full study guide library linked at the end to keep the drills fresh. For administrative matters such as exam scheduling, formats, and any remotely proctored options, go directly to the issuing organization's website rather than relying on summaries.
| Aspect | Air framework | Sea framework | Ground framework |
|---|---|---|---|
| Regulatory base | Derived from the UN Model Regulations with air-specific rules | Derived from the UN Model Regulations for maritime transport | Derives from the UN Model Regulations; wording varies by country |
| Core document | Shipper's declaration for dangerous goods in its prescribed form | Sea-transport documentation conventions on the transport document | National ground documentation with its own conventions |
| Quantity relief pathways | Defined within the air rulebook; check eligibility per substance | Limited and excepted quantity provisions defined for sea | Limited quantity provisions defined nationally; availability varies |
| Where divergence bites | Packing instructions and quantity caps are mode-specific | Stowage and segregation take on maritime specifics | Thresholds and notations can differ between countries |
References and further reading
Use these references to explore the concepts and check the latest information from the relevant organizations.