Unified Interpretations


Unified Interpretations are adopted resolutions on matters arising from implementing the requirements of IMO Conventions or Recommendations. Such adopted resolutions can involve uniform interpretations of Convention Regulations or IMO Resolutions on those matters which in the Convention are left to the satisfaction of the Administration or vaguely worded.

Interpretations are circulated to Administrations concerned or are sent to IMO for information, as appropriate.


  1. IACS, as an international Non-Governmental Organization having observer status at IMO, works in co-operation with IMO in order to endeavour that regulations developed at IMO are clear, unambiguous and can easily be applied without the need of interpretations.
  2. However, interpretations may still be needed in cases where IMO regulations contain only functional requirements, allow alternative solutions to prescriptive requirements, are left to the satisfaction of Administrations or are generally or vaguely worded.
  3. The following Unified Interpretations (UIs) have been developed by IACS to assist the unified implementation of IMO regulations falling in the above-mentioned cases. It should be noted that the development of IACS Unified Interpretations (UIs) is not aiming at introducing additional requirements but at achieving uniform application of IMO regulations.
  4. IACS UIs are to be applied by IACS Societies to ships whose flag Administrations have not issued definite instructions on the interpretation of the IMO regulations concerned, in the course of statutory certification on behalf of those flag Administrations.

The technical backgrounds (development histories) of Unified Interpretations since 2004 can be found by following this link.

A list of the IACS working groups responsible for each Unified Interpretation may be found here.

UI MPC84 Deleted

UI MPC84 Annex VI of MARPOL 73/78 Regulation 16 (9) Deleted Nov 2013


UI MPC85 Regulation 22(5), Annex I of MARPOL 73/78 as amended by resolution MEPC.117(52) Regulation 22, Pump-room bottom protection - Rev.4 September 2008

UI MPC86 Corr1 CLN

UI MPC86 Annex IV of MARPOL 73/78 Regulation 10.1 as amended by Resolution MEPC.115(51) Standard Discharge Connection - Corr.1 October 2007

UI MPC87 New

UI MPC87 Annex I of MARPOL 73/78 Regulation 12A as amended by Resolution MEPC.141(54) Regulation 12A.9, as amended by Resolution MEPC.141(54) - January 2007


UI MPC88 Annex IV of MARPOL 73/78 Regulation 9.1.1 Regulation 9 Sewage systems - Rev.1 December 2015 Clean

UI MPC90 New

UI MPC90 Annex I of MARPOL 73/78 Regulation 1 as amended by Resolution MEPC.117(52) Regulation 1.28.1 to 1.28.8, as amended by Resolution MEPC.117(52) - September 2007

UI MPC91 New


UI MPC92 New

UI MPC92 Tonnage to be used when applying MARPOL Annex VI Regulation 5 Surveys and Inspections - October 2007


UI MPC93 Annex I of MARPOL 73/78 Regulation 23 Accidental oil outflow performance, as amended by Resolution MEPC.117(52) Regulation, as amended by Resolution MEPC.117(52) - Rev.1 April 2016 Clean

UI MPC94 New

UI MPC94 Annex I of MARPOL 73/78 Regulation 12A.6-8 and 11.8 Oil Fuel Tank Protection, as amended by Resolution MEPC.141(54) Regulation 12A.6-8 and 11.8 as Amended by Resolution MEPC.141(54) - July 2008

UI MPC95 New

UI MPC95 Measurement of Distances - August 2008

UI MPC96 Deleted

UI MPC96 Initial Statutory Surveys at New Construction Deleted June 2016

UI MPC97 New

UI MPC97 Volatile Organic Compounds (VOCs) Management Plan MARPOL VI, Regulation 15.6 and 15.7 - July 2010

UI MPC98 New

UI MPC98 “Time of the Replacement or Addition” for the Applicable Tier Standard For the Supplement to the IAPP Certificate - January 2012

UI MPC99 New

UI MPC99 Oil residue (sludge) tank discharge connections to the bilge system, oily bilge water holding tank(s), tank top or oily water separators (MARPOL 73/78 Annex I Regulation 12.2) MARPOL 73/78 Annex I (as amended by MEPC.187(59)) Regulation 12.2 - July 2011

UI MPC100 New

UI MPC100 Date of Delivery under SOLAS and MARPOL Conventions - June 2012

UI MPC101 New

UI MPC101 Supplement to the International Air Pollution Prevention (IAPP) Certificate – Section 2.3 - July 2012

UI MPC102 New

UI MPC102 Surveys and certification relating to the Ship Energy Efficiency Management Plan (SEEMP) (MARPOL Annex VI Regulation 5.4.4) - July 2012

UI MPC103 New

UI MPC103 - Identical Replacement Engines (MARPOL Annex VI Regulation 13) - January 2013

UI MPC104 Corr1 CLN

UI MPC104 Keel Laying Date for Fibre-Reinforced Plastic (FRP) Craft - Corr.1 Jan 2014

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