INSTITUTION PROFILE / HYDROGEN ENERGY
International Maritime Organization (IMO)
The UN body that sets ship greenhouse gas and fuel safety rules by treaty. Its net-zero framework is approved but not adopted, with adoption not before December 2026
The International Maritime Organization (IMO) is a United Nations specialised agency that sets safety and environmental rules for international shipping through treaties and regulations. For hydrogen energy, two things matter: the regulation of ship greenhouse gas (GHG) emissions (the IMO Net-Zero Framework) and the safety rules for using hydrogen, ammonia, methanol and similar fuels on ships (the IGF Code and a series of interim guidelines). But the IMO is the forum where rules are adopted; flag States and port States are the ones that inspect and penalise ships. The Net-Zero Framework was approved in April 2025, but adoption was adjourned for a year in October 2025, and as of 5 October 2026 it is neither adopted nor in force. This profile looks at one question only: how much influence the IMO actually has over hydrogen energy, keeping the stages of approval, adoption and entry into force strictly apart. It contains no advice on handling any ship or fuel.
What this article covers
- The IMO in 30 seconds
- What kind of body it is: the four types of influence
- What it does for hydrogen energy
- How far its influence reaches (powers and geography)
- Who it works with
- Outlook
- Glossary, references and claim-to-source audit
1. The IMO in 30 seconds
FULL NAMEInternational Maritime OrganizationA UN specialised agency. The Secretary-General is Arsenio Dominguez (in office since 1 January 2024, for a four-year term)
REGIONInternational organisation (London)176 Member States and three Associate Members. 68 intergovernmental organisations have observer status
TYPE OF BODYUN specialised agencyIts convention was adopted in Geneva on 6 March 1948 and entered into force in 1958; the Organization first met the following year
STAFFAbout 300 international staffThe Secretary-General and the international staff at the London headquarters (the IMO's description)
BUDGETGBP 87.43 million for 2026-2027Of which GBP 76.84 million is Member State contributions, which depend mainly on the tonnage of each State's merchant fleet
ROLE IN HYDROGEN ENERGYGHG rules and fuel safety rulesMARPOL Annex VI (the Net-Zero Framework), SOLAS and the IGF Code, and interim guidelines
LEGAL FORCETreaties bind parties; guidelines do notThe IMO is where rules are set; inspection and penalties are for flag and port States
REACHShips in international trade (over 80% of world trade)It has no power over hydrogen production or use on land, or over fuel production
The one thing to grasp first
The Net-Zero Framework has to be read stage by stage. (1) July 2023 (MEPC 80): the "2023 IMO GHG Strategy" was adopted (a framework of goals, not treaty text that binds ships directly). (2) April 2025 (MEPC 83): the draft legal text of the Net-Zero Framework (a new Chapter 5 of MARPOL Annex VI) was approved. (3) 14 to 17 October 2025 (MEPC/ES.2): the session meant to consider adoption was adjourned for a year. (4) April to May 2026 (MEPC 84): an intersessional working group was set up again, and ES.2 is to resume on 4 December 2026 (subject to confirmation by MEPC 85). (5) If adopted, under the tacit acceptance procedure the IMO says the measures are expected to enter into force 16 months after adoption Sourced. So, as of 5 October 2026, the Net-Zero Framework is approved, not adopted, not in force. The safety rules for using hydrogen as a ship fuel run on a separate track: the interim guidelines for hydrogen were approved by MSC 111 in May 2026, which makes them guidelines, not treaty text.
2. What kind of body it is: the four types of influence
Unlike the companies in this series, none of the institutions that appear in hydrogen coverage produces hydrogen. What separates them is the route by which they influence the industry, and that gives four types. The IMO is an international body of the "Policy & regulation" type: by agreement among its members it makes international rules for one limited field, ships.
3. What it does for hydrogen energy
The IMO's involvement in hydrogen has two strands: regulation of ship GHG emissions and safety rules for using hydrogen and similar fuels on ships. In both, an IMO committee (MEPC for the environment, MSC for safety) drafts the rule, which then moves through approval, adoption and entry into force Sourced.
GHG regulation: from strategy to framework (keeping the stages apart)
| Item | Stage | What the primary sources say | Category |
|---|---|---|---|
| 2023 IMO GHG Strategy | Adopted (July 2023, MEPC 80) | A framework for Member States. It aims for international shipping to reach net-zero GHG emissions "by or around, i.e. close to, 2050". Checkpoints against 2008: at least 20% (striving for 30%) lower by 2030 and at least 70% (striving for 80%) by 2040. Zero or near-zero GHG emission technologies, fuels and energy sources to make up at least 5% (striving for 10%) of the energy used by international shipping by 2030. Carbon intensity to fall at least 40% by 2030 against 2008 | Sourced |
| Short-term measures (EEXI and CII) | In force (November 2022) | Technical and operational requirements adopted by MEPC 76 in June 2021 as amendments to MARPOL Annex VI, aimed at cutting carbon intensity at least 40% by 2030 against 2008. A review is to be completed by 1 January 2026 | Sourced |
| IMO Net-Zero Framework | Approved, not adopted, not in force | Draft text of a new Chapter 5 of MARPOL Annex VI, with two linked parts: a global fuel standard (a limit on the life-cycle GHG intensity of fuels that tightens each year) and a GHG pricing mechanism. It covers oceangoing ships over 5,000 gross tonnage (over 85% of international shipping emissions). A ship above the limit must cover the deficit with surplus units or by paying into the IMO Net-Zero Fund. Zero or near-zero (ZNZ) fuels have a GHG intensity of 19.0 gCO2eq/MJ or less, 80% below the current average of 93.3 | Sourced |
| How the Framework has progressed | Approved (April 2025), adoption adjourned, to resume | MEPC 83 approved the draft text in April 2025. The extraordinary session MEPC/ES.2 (14 to 17 October 2025), convened to consider adoption, was adjourned for 12 months. MEPC 84 (27 April to 1 May 2026) set up a working group; after ISWG-GHG 22 (1 to 4 September 2026, held) and ISWG-GHG 23 (23 to 27 November 2026), the matter goes to MEPC 85 (30 November to 3 December 2026). ES.2 is to resume on 4 December 2026, subject to confirmation by MEPC 85 | Sourced Not yet confirmed |
| Expected entry into force | After adoption (not yet reached) | Amendments to MARPOL go through the tacit acceptance procedure. If adopted, the IMO says the measures are expected to enter into force 16 months after adoption, after which governments enforce them | Not yet confirmed |
* The IMO's FAQ describes the Framework as "a market-based system built around performance targets and tiered compliance fees", not a uniform global carbon tax. Compliance is measured by life-cycle (well-to-wake) GHG intensity, not by fuel type, so which fuels come out ahead depends on the final wording and on fuel certification guidelines Not yet confirmed.
Fuel safety rules: hydrogen, ammonia, methanol
| Item | Stage | What the primary sources say | Category |
|---|---|---|---|
| IGF Code | Mandatory (under SOLAS); amendments in progress | The international standard for ships using gases or other low-flashpoint fuels, written around natural gas. In December 2024 MSC 109 adopted amendments to parts A and A-1, expected to enter into force on 1 January 2028. MSC 109 also approved draft SOLAS chapter II-1 amendments clarifying that the IGF Code applies to gaseous or low-flashpoint fuels, and MSC 110 aimed for amendments with a new definition of "gaseous fuel" to be adopted at MSC 112 (2026) and enter into force on 1 July 2028 | Sourced Not yet confirmed |
| Ships using hydrogen as fuel | Interim guidelines (approved, May 2026) | MSC 111 (13 to 22 May 2026) approved the Interim Guidelines for the safety of ships using hydrogen as fuel. They are guidelines, not treaty text | Sourced |
| Ships using ammonia as fuel | Interim guidelines (approved, May 2026) | CCC 10 (September 2024) finalised the draft, and MSC 111 approved the Interim Guidelines for the safety of ships using ammonia as fuel and interim guidelines on training seafarers for ammonia-fuelled ships | Sourced |
| Ships using methyl/ethyl alcohol (methanol) as fuel | Interim guidelines (approved earlier) | Interim guidelines MSC.1/Circ.1621. MSC 111 also approved interim training guidelines for seafarers | Sourced |
| Ships with fuel cells, ships using LPG as fuel | Interim guidelines (approved earlier) | Fuel cells: MSC.1/Circ.1647. LPG: MSC.1/Circ.1666 | Sourced |
| Liquefied hydrogen carried as cargo | Revised interim recommendations (adopted, May 2024) | MSC 108 adopted the revised interim recommendations for the carriage of liquefied hydrogen in bulk. This is about cargo (the IGC Code's field) and is separate from fuel rules | Sourced |
| Identifying regulatory gaps | Work in progress | A correspondence group on GHG safety found 51 gaps and barriers in existing rules and made 32 recommendations. MSC 110 updated these and assigned tasks to the CCC, SDC and SSE sub-committees, and decided to tell ISO/TC 8 of standards gaps concerning ammonia and other fuels | Sourced |
| Cryogenic metallic materials | Guidelines (approved) | MSC 108 approved revisions to the guidelines on high manganese austenitic steel for cryogenic service (MSC.1/Circ.1599/Rev.2) and on accepting alternative metallic materials for cryogenic service in ships carrying liquefied gases and ships using gases or other low-flashpoint fuels (MSC.1/Circ.1622) | Sourced |
A materials engineer's view: materials criteria are most developed for cryogenic metals
The cryogenic metallic materials guidelines approved by MSC 108 bear on the acceptance of materials for tanks that hold liquefied gas as cargo or fuel Sourced. The requirements for using hydrogen or ammonia as a ship fuel, by contrast, are at the stage of the interim guidelines approved in May 2026, not mandatory rules. How materials for hydrogen fuel tanks and piping (including resistance to hydrogen embrittlement) will become treaty-level criteria is something we could not confirm Not yet confirmed. For the technical background, see our explainers on liquid hydrogen, ammonia, methanol, high-pressure hydrogen tanks, and barrier properties and coatings.
4. How far its influence reaches (powers and geography)
| Aspect | What the IMO has | What it does not have |
|---|---|---|
| Powers: rules | It is the forum where Member States adopt treaties on ship safety (SOLAS), the environment (MARPOL) and training (STCW), and their mandatory codes (such as the IGF Code). It also approves non-mandatory guidelines and interim guidelines | The power to make rules on its own (Member State agreement is required). Guidelines are not treaty text |
| Powers: enforcement | None. The IMO helps Member States with technical assistance to bring treaties into national law | Inspecting and policing ships (flag States and port States do that). An IMO treaty applies to ships only once it has been implemented in national law |
| Procedure | For MARPOL amendments the steps are approval, circulation, adoption, deemed acceptance, entry into force and enforcement. The Net-Zero Framework is expected to enter into force 16 months after adoption | The power to apply a proposal that has not been adopted |
| Geography | Ships in international trade. 176 Member States. International shipping carries over 80% of world trade | Rules for producing, moving or using hydrogen on land, or for fuel production and prices. Port development is limited to inviting voluntary cooperation |
| Scale | About 300 international staff. A budget of GBP 87.43 million for 2026-2027 | We could not confirm a hydrogen-specific budget or staff number |
Easily confused: "approved", "adopted", "in force" and "guidelines"
IMO documents distinguish approved (a committee accepts a draft and circulates it), adopted (Member States formally decide) and in force (it legally applies). The Net-Zero Framework has been approved but not adopted. And the interim guidelines for hydrogen and ammonia approved by MSC 111 are guidelines, not mandatory rules like the IGF Code. When you meet a phrase such as "the IMO has set hydrogen ship standards" or "the IMO has decided on net zero", check which stage it describes Sourced.
5. Who it works with
The IMO is run by its member governments, and it is not an institution tied directly to companies. Industry and non-governmental bodies take part in meetings as observers. The diagram below shows only institutional relationships that the primary sources document. This article does not cover individual shipping companies or manufacturers.
| Body | Relationship to the IMO (primary sources) |
|---|---|
| Member States (flag and port States) | They bring treaties into national law and apply them as flag States to ships on their registers and as port States to ships entering their ports. If the Net-Zero Framework enters into force, governments enforce it |
| MEPC, MSC and sub-committees (CCC, SDC, SSE and others) | MEPC handles ship pollution and GHG emissions and MSC handles safety. Sub-committees such as the CCC prepare the technical drafts on fuel safety |
| International Organization for Standardization (ISO) | Ship standards fall under ISO/TC 8. MSC 110 decided to inform ISO of gaps in standards for fuels such as ammonia |
| Intergovernmental organisations and NGOs (observers) | 68 intergovernmental organisations hold observer status, and non-governmental organisations also take part |
| IMO Net-Zero Fund (proposed) | A fund that would receive and disburse revenue from GHG pricing if the Framework is adopted and enters into force. A governing board would oversee it and report to MEPC. For now it is a proposal |
Our technology explainers on ammonia, methanol, liquid hydrogen, hydrogen colours and carbon intensity, and high-pressure hydrogen tanks cover the technology of hydrogen-based fuels that ships might use. Our company profiles cover firms involved in hydrogen and its derivative fuels.
6. Outlook
| What can be read from the sources | Primary evidence | Category |
|---|---|---|
| ISWG-GHG 23 is set for 23 to 27 November 2026, and MEPC 85 for 30 November to 3 December 2026 | The summaries of MEPC 84 and ISWG-GHG 22. ISWG-GHG 22 ran out of time and deferred the guidelines to ISWG-GHG 23 | Not yet confirmed |
| MEPC/ES.2 is planned to resume on 4 December 2026, and the resumption itself is subject to confirmation by MEPC 85 | The summary of MEPC 84 | Not yet confirmed |
| If the Net-Zero Framework is adopted, it is expected to enter into force 16 months after adoption | The IMO's FAQ and the MEPC 83 summary. MEPC 84 allowed Member States to submit new amendments, so the content may change | Not yet confirmed |
| The IGF Code amendments to parts A and A-1 are expected to enter into force on 1 January 2028 | The MSC 109 summary (adopted; entry into force is in the future) | Not yet confirmed |
| The SOLAS chapter II-1 and IGF Code amendments on "gaseous fuel" were aimed at adoption at MSC 112 (December 2026) and entry into force on 1 July 2028 | The MSC 110 summary. We could not confirm whether MSC 111 approved them | Not yet confirmed |
| Safety rules for hydrogen-fuelled ships may stay at the interim-guideline stage for some time before becoming mandatory rules | MSC 111 approved interim guidelines, and we found no mandatory hydrogen-specific rule like the IGF Code. The IMO is still working through regulatory gaps (MSC 110) | Inference |
| The longer adoption of the Net-Zero Framework is delayed, the more shipowners' and fuel suppliers' investment decisions may be put off | Adoption slipped from October 2025 to December 2026 at the earliest (MEPC/ES.2 and MEPC 84). We did not check any individual investment decision | Inference |
7. Glossary
- MEPC / MSC
- The IMO's Marine Environment Protection Committee (MEPC) and Maritime Safety Committee (MSC). MEPC deals with pollution and GHG emissions from ships, MSC with ship safety.
- MARPOL Annex VI
- The rules for preventing air pollution from ships. The GHG short-term measures and the draft Net-Zero Framework are treated as amendments to this annex.
- SOLAS / IGF Code
- The Safety of Life at Sea convention (SOLAS) and, under it, the mandatory international standard for ships using gases or other low-flashpoint fuels (the IGF Code).
- Interim guidelines
- Documents approved as guidance while experience with a new fuel builds up (MSC circulars). They are not treaty text and are not mandatory.
- Approval / adoption / entry into force
- Approval is a committee accepting a draft; adoption is Member States formally deciding; entry into force is when it legally applies.
- Tacit acceptance procedure
- The way amendments to MARPOL and similar treaties are deemed accepted, and enter into force, unless enough parties object within a set period.
- GFI / ZNZ fuel
- GFI is a fuel's life-cycle GHG intensity (gCO2eq/MJ). ZNZ fuels are zero or near-zero GHG emission fuels, which the Framework puts at about 19.0 gCO2eq/MJ or less.
- Flag State / port State
- The flag State is where a ship is registered; the port State is where it calls. They apply IMO treaties in national law and inspect and police ships.
8. References
- IMO Introduction to IMO (UN specialised agency, role, over 80% of world trade). https://www.imo.org/en/About/Pages/Default.aspx
- IMO FAQs (establishment, Secretary-General, about 300 international staff, national implementation of treaties and port State control). https://www.imo.org/en/About/Pages/FAQs.aspx
- IMO History of IMO (1948 conference, entry into force in 1958). https://www.imo.org/en/About/HistoryOfIMO/Pages/Default.aspx
- IMO Structure (Assembly, Secretariat, budget for 2026-2027). https://www.imo.org/en/About/Pages/Structure.aspx
- IMO Membership (176 Member States, three Associate Members, 68 observer intergovernmental organisations). https://www.imo.org/en/About/Membership/Pages/Default.aspx
- IMO 2023 IMO Strategy on Reduction of GHG Emissions from Ships (July 2023, MEPC 80: goals, checkpoints, short-term measures). https://www.imo.org/en/ourwork/environment/pages/2023-imo-strategy-on-reduction-of-ghg-emissions-from-ships.aspx
- IMO The IMO Net-Zero Framework - FAQs (content, ships covered, procedure, expected entry into force, ZNZ fuels, fund). https://www.imo.org/en/mediacentre/hottopics/pages/faqs-the-imo-net-zero-framework.aspx
- IMO MEPC 83 (7 to 11 April 2025: approval of the Net-Zero Framework; entry into force expected 16 months after adoption). https://www.imo.org/en/MediaCentre/MeetingSummaries/Pages/MEPC-83rd-session.aspx
- IMO MEPC 2nd extraordinary session (14 to 17 October 2025: adjournment). https://www.imo.org/en/MediaCentre/MeetingSummaries/Pages/MEPC-ES-2.aspx
- IMO MEPC 84th session (27 April to 1 May 2026: working group, MEPC 85, planned resumption of ES.2). https://www.imo.org/en/MediaCentre/MeetingSummaries/Pages/Temporary-MEPC-84th-session.aspx
- IMO ISWG-GHG 22 (1 to 4 September 2026). https://www.imo.org/en/MediaCentre/MeetingSummaries/Pages/iswg-ghg-22.aspx
- IMO IGF Code (description of the international standard for ships using gases or other low-flashpoint fuels). https://www.imo.org/en/ourwork/safety/pages/igf-code.aspx
- IMO MSC 111th session - highlights (13 to 22 May 2026: approval of interim guidelines for hydrogen and ammonia). https://www.imo.org/en/MediaCentre/MeetingSummaries/Pages/Temporary-MSC-111.aspx
- IMO MSC 110th session (2025: regulatory gaps, clarifying the application of the IGF Code, notice to ISO/TC 8). https://www.imo.org/en/MediaCentre/MeetingSummaries/Pages/msc-110th-session.aspx
- IMO MSC 109th session (December 2024: adoption of IGF Code amendments, approval of draft SOLAS chapter II-1 amendments). https://www.imo.org/en/MediaCentre/MeetingSummaries/Pages/MSC-109th-session.aspx
- IMO MSC 108th session (May 2024: interim recommendations for liquefied hydrogen carriage, cryogenic materials guidelines). https://www.imo.org/en/MediaCentre/MeetingSummaries/Pages/MSC-108th-session.aspx
- IMO CCC 10th session (September 2024: draft interim guidelines for ammonia, existing interim guidelines). https://www.imo.org/en/MediaCentre/MeetingSummaries/Pages/ccc-10th-session.aspx
9. Claim-to-source audit
| Claim in the article | Category | Source |
|---|---|---|
| UN specialised agency, its role, and international shipping carrying over 80% of world trade | Sourced | Reference 1 https://www.imo.org/en/About/Pages/Default.aspx |
| The founding convention (adopted 6 March 1948), Secretary-General Arsenio Dominguez (since 1 January 2024), about 300 international staff, national implementation of treaties and port State control | Sourced | Reference 2 https://www.imo.org/en/About/Pages/FAQs.aspx |
| Entry into force of the convention (1958) and the first meeting (the following year) | Sourced | Reference 3 https://www.imo.org/en/About/HistoryOfIMO/Pages/Default.aspx |
| The 2026-2027 budget of GBP 87.43 million, Member State contributions of GBP 76.84 million, and how they are set | Sourced | Reference 4 https://www.imo.org/en/About/Pages/Structure.aspx |
| 176 Member States, three Associate Members, 68 observer intergovernmental organisations | Sourced | Reference 5 https://www.imo.org/en/About/Membership/Pages/Default.aspx |
| The 2023 IMO GHG Strategy (adopted July 2023): goals and checkpoints; the short-term measures (in force November 2022) and their review by 1 January 2026; voluntary port cooperation | Sourced | Reference 6 https://www.imo.org/en/ourwork/environment/pages/2023-imo-strategy-on-reduction-of-ghg-emissions-from-ships.aspx |
| The Net-Zero Framework content (fuel standard and pricing, ships over 5,000 gross tonnage, ZNZ fuels at 19.0 gCO2eq/MJ, fund), procedure and entry into force 16 months after adoption | Sourced | Reference 7 https://www.imo.org/en/mediacentre/hottopics/pages/faqs-the-imo-net-zero-framework.aspx |
| Approval by MEPC 83 in April 2025; expected entry into force 16 months after adoption | Sourced | Reference 8 https://www.imo.org/en/MediaCentre/MeetingSummaries/Pages/MEPC-83rd-session.aspx |
| Adjournment of MEPC/ES.2 (14 to 17 October 2025) for 12 months | Sourced | Reference 9 https://www.imo.org/en/MediaCentre/MeetingSummaries/Pages/MEPC-ES-2.aspx |
| MEPC 84 decisions (working group, two ISWG-GHG meetings, MEPC 85, ES.2 to resume on 4 December 2026) | Not yet confirmed | Reference 10 https://www.imo.org/en/MediaCentre/MeetingSummaries/Pages/Temporary-MEPC-84th-session.aspx |
| ISWG-GHG 22 held on 1 to 4 September 2026, with items deferred to ISWG-GHG 23 | Sourced | Reference 11 https://www.imo.org/en/MediaCentre/MeetingSummaries/Pages/iswg-ghg-22.aspx |
| The IGF Code as a mandatory standard | Sourced | Reference 12 https://www.imo.org/en/ourwork/safety/pages/igf-code.aspx |
| Approval of interim guidelines for hydrogen and ammonia (MSC 111, May 2026) and training guidelines for ammonia and methanol | Sourced | Reference 13 https://www.imo.org/en/MediaCentre/MeetingSummaries/Pages/Temporary-MSC-111.aspx |
| Regulatory gaps (51 gaps, 32 recommendations), notice to ISO/TC 8, aim to adopt the IGF Code clarification at MSC 112 and bring it into force on 1 July 2028 | Sourced | Reference 14 https://www.imo.org/en/MediaCentre/MeetingSummaries/Pages/msc-110th-session.aspx |
| Adoption of IGF Code parts A and A-1 amendments (entry into force expected 1 January 2028); approval of draft SOLAS chapter II-1 amendments | Sourced | Reference 15 https://www.imo.org/en/MediaCentre/MeetingSummaries/Pages/MSC-109th-session.aspx |
| Revised interim recommendations for bulk carriage of liquefied hydrogen (adopted); approval of cryogenic metallic materials guidelines | Sourced | Reference 16 https://www.imo.org/en/MediaCentre/MeetingSummaries/Pages/MSC-108th-session.aspx |
| Draft interim guidelines for ammonia finalised; interim guidelines for methanol (Circ.1621), fuel cells (Circ.1647) and LPG (Circ.1666) | Sourced | Reference 17 https://www.imo.org/en/MediaCentre/MeetingSummaries/Pages/ccc-10th-session.aspx |
| The four types of institution and the arrangement of Fig. 2 | Our calculation | Our own classification |
| That the IMO does not inspect or police ships (flag and port States enforce) | Our calculation | Our own summary of reference 2 (treaties are brought into national law, and port State control is exercised) |
| When the Net-Zero Framework will be adopted, its final content and any entry-into-force date | Not yet confirmed | Not adopted as of 5 October 2026. Dates cannot be fixed before adoption, so this article does not estimate them |
| The circular number of the hydrogen interim guidelines, and whether a mandatory hydrogen-specific rule exists | Not yet confirmed | Reference 13 gives no number, and we found no mandatory hydrogen-specific rule. This article does not guess |
| The current status of the SOLAS chapter II-1 and IGF Code amendment planned for adoption at MSC 112 | Not yet confirmed | Not mentioned in the MSC 111 highlights (reference 13); this article does not guess |
| A hydrogen-specific budget or staff number | Not yet confirmed | Not found on the official pages; this article does not estimate them |
| The two points marked as inference in section 6, and the inference in the materials engineer's view | Inference | This article's reading of the stages and content in references 7, 10, 13 and 14 |
Last updated 5 October 2026 / Troy Technical
This article draws on the IMO's website and meeting summaries. The stages of approval, adoption and entry into force are distinguished as the IMO describes them. Items marked "Inference" are this article's reading of the primary information. This is an explanation of rules, not advice on any ship or fuel.