Extended Operational and Trade Vocabulary

IACS, Class Rules and Class Notations glossary

The classification societies and the notations they assign: ABS and IACS-member founding history, principal hull notations (A1), machinery notations (AMS, ACCU, ACC), and the Common Structural Rules. Grounds each notation in the survey regime and rule set it certifies, from unrestricted service to unattended machinery space operation.

233 defined terms.

A

ABS: American Bureau of Shipping; IACS member classification society.
ABS A1: ABS principal hull classification notation for vessels built and maintained to ABS Rules for unrestricted service.
ABS ACC: ABS notation for centralized control of propulsion machinery from a continually manned control station.
ABS ACCU: ABS notation for automatic control of machinery in unattended centralized control, periodically unattended machinery space.
ABS AMS: ABS notation for machinery built, installed and tested per ABS Rules under the Automated Machinery Space program.
ABS BCA: ABS notation indicating a bulk carrier built to Common Structural Rules.
ABS CSR: ABS notation appended to class for vessels built to IACS Common Structural Rules.
ABS ENVIRO+: ABS environmental protection notation recognising design and operational measures beyond statutory minima.
ABS NIBS: ABS Navigation and Integrated Bridge System notation for integrated navigation arrangements.
ABS SH: ABS SafeHull notation for vessels designed under the ABS SafeHull dynamic load and finite-element methodology.
ABS SH-DLA: ABS SafeHull Dynamic Loading Approach notation for ships analyzed by spectral-based direct calculation.
ABS Steel Vessel Rules: ABS Rules for Building and Classing Marine Vessels, the principal ABS classification rulebook.
Acceptance Testing: shipyard and class verification that systems, structures and equipment meet rule requirements before delivery.
Additional Class Notation: a notation appended to the main class symbol denoting optional or service-specific compliance.
Allowable Hold Loading: maximum permissible cargo mass per hold derived per IACS UR-S22 for bulk carriers.
Annual Survey (AS): Statutory or class survey performed yearly within a three-month window of anniversary date.
Anti-Fouling Systems Certificate: statutory certificate issued under IMO AFS Convention, typically by RO on flag behalf.
Approval in Principle (AiP): class statement that a novel concept is feasible against applicable rules pending detailed design.
Arc4: Russian Maritime Register of Shipping ice category, light first-year ice, Polar Class broadly equivalent to PC7.
Arc5: RS ice category, medium first-year ice, broadly equivalent to PC6 range.
Arc6: RS ice category, heavy first-year ice, broadly equivalent to PC5 range.
Arc7: RS ice category, year-round in first-year ice, broadly equivalent to PC4 range.
Arc8: RS ice category for heavier multi-year incursions, broadly equivalent to PC3 range.
Arc9: RS highest non-icebreaker ice category, broadly equivalent to PC2 range.
As-Built Drawings: Original construction plans used as reference for structural and gauging surveys.

B

Ballast Water Management (BWM): DNV and other class notation for compliance with ballast water treatment requirements.
BIS: DNV Built for In-water Survey notation indicating design features enabling underwater inspection in lieu of drydocking.
Block coefficient (CB): Ratio of displaced volume to L*B*T.
Builder's Certificate: Statement by the shipyard certifying particulars and first ownership of a newly built ship, used at first registration.
Bulk carrier additional survey: Expanded inspection element under Paris MoU NIR applied to bulk carriers older than 12 years.
Bureau Veritas (BV): French classification society, founded 1828, IACS founding member.
BV Coastal Area: BV navigation notation restricting service to coastal voyages within defined distance from shore.
BV I HULL MACH: BV main class notation for hull and machinery surveyed under BV Rules.
BV Unrestricted Navigation: BV navigation notation for worldwide service without geographic restriction.

C

CAS: Condition Assessment Scheme for single-hull oil tankers under MARPOL Annex I Regulation 20.
CCS: Cargo Containment System under the IGC and IGF Codes.
Certificate of Class: Document issued by class confirming the vessel is in class.
CHS: Continuous Hull Survey, cyclical scheme spreading special survey items over five years.
Class Maintenance: ongoing compliance through periodic surveys, conditions and recommendations.
Class Notation: Class society designation reflecting compliance with construction and equipment rules incorporated into SOLAS by reference.
Class Renewal Survey: Five yearly comprehensive class survey equivalent to Special Survey.
Class suspension: Withdrawal of class status by a classification society, often triggering loss of statutory certificates.
Class Transfer: change of classification society subject to IACS Procedure for Transfer of Class (TOCA).
Class withdrawal: Permanent cancellation of class by a classification society.
CLEAN: DNV environmental notation recognising design features limiting operational emissions and discharges.
CLEAN DESIGN: DNV enhanced environmental notation with stricter design and equipment criteria.
Close-Up Survey (CUS): examination where structural details are within reach of the surveyor under ESP.
CMS: Continuous machinery survey, alternative class survey regime.
Common Procedural Rules (CPR): IACS procedures for survey, certification and class maintenance applied across members.
Common Structural Rules (CSR): IACS unified scantling rules for bulk carriers and oil tankers in force since 1 April 2006.
Conditions of Class: requirements to take corrective action within a defined time to retain class.
Continuous Survey: cyclical alternative to special survey for hull or machinery items.
Corrugated Transverse Watertight Bulkhead: bulk carrier bulkhead governed by IACS UR-S18 scantling evaluation.
Croatian Register of Shipping (CRS): IACS member, headquartered Split, Croatia.
CSR-BC: IACS Common Structural Rules for Bulk Carriers, first edition 1 April 2006.
CSR-H: harmonised IACS Common Structural Rules for Bulk Carriers and Oil Tankers, adopted 2014, in force 1 July 2015 for new contracts.
CSR-OT: IACS Common Structural Rules for Double Hull Oil Tankers, first edition 1 April 2006.
Cyber Resilience: design and operational property addressed by IACS UR-E26 and UR-E27.

D

Damage Survey: Investigation into hull, machinery, or cargo damage and probable cause.
DNV: Det Norske Veritas (DNV); IACS member classification society.
DNV 1A: DNV main class notation for unrestricted service vessels under DNV Rules.
DNV BIS: notation for vessels built for in-water survey.
DNV BWM: ballast water management notation.
DNV CLEAN: environmental class notation.
DNV GAS FUELLED: notation for ships designed to use natural gas as fuel under IGF-aligned DNV Rules.
DNV ICE-1A: DNV ice class corresponding to Finnish-Swedish Ice Class IA.
DNV ICE-1A Super: DNV notation equivalent to Finnish-Swedish Ice Class IA Super.
DNV ICE-1B: DNV notation equivalent to Finnish-Swedish Ice Class IB.
DNV ICE-1C: DNV notation equivalent to Finnish-Swedish Ice Class IC.
DNV LCS: DNV Lashing Computer System notation.
DNV NAUT-OSV: DNV navigation arrangements notation for offshore support vessels.
DOC: Document of Compliance issued to company under the ISM Code.
Drydock Survey: Out-of-water survey of underwater hull, rudder, propeller, and sea valves.
Dual Class: simultaneous classification with two IACS members under a dual class agreement.

E

ECDIS: Electronic Chart Display and Information System per IMO MSC.232(82).
ECO: Lloyd's Register environmental descriptive notation.
Enhanced Survey Programme (ESP): Mandatory close-up and gauging regime for tankers and bulk carriers.
Equivalent Arrangement: alternative to rule requirement accepted by class on demonstration of equivalent safety.
ESP Bulk Carrier: ESP regime applied to single and double side skin bulk carriers.
ESP Code: IMO 2011 ESP Code (resolution A.1049(27), as amended) consolidating ESP requirements.
ESP Oil Tanker: ESP regime applied to crude and product oil tankers.
Exemption Certificate: Statutory document showing flag-granted exemption; verified during surveys.

F

Finnish-Swedish Ice Class IA: ice class for navigation in severe ice with occasional icebreaker assistance.
Finnish-Swedish Ice Class IA Super: highest Finnish-Swedish ice class for navigation in difficult Baltic ice without icebreaker assistance.
Finnish-Swedish Ice Class IB: ice class for navigation in medium ice with icebreaker assistance.
Finnish-Swedish Ice Class IC: ice class for navigation in light ice with icebreaker assistance.
Finnish-Swedish Ice Class II: notation for steel ships of normal design suited only to very light ice.
Finnish-Swedish Ice Class III: notation for ships not meeting II requirements.
Fire Safety Construction: structural fire protection per SOLAS Chapter II-2, verified by RO surveys.
First Class Entry: initial classification of a new building on delivery.
Founding Members of IACS: ABS, BV, DNV, GL, LR, NK, RINA, RS, signatories of the 11 September 1968 establishment.

G

GAS FUELLED: DNV notation for ships designed to operate on natural gas fuel.
General Dry Cargo Ship Rules: IACS UR-S25, longitudinal strength requirements for general dry cargo ships.
Germanischer Lloyd (GL): former IACS founding member, merged with DNV in 2013.
GRAB Notation: CSR-BC notation indicating hold structure verified for specified unloading grab mass.

H

Harmonised CSR: see CSR-H, IACS harmonised rules for bulk carriers and oil tankers.
Harmonized System of Survey and Certification (HSSC): IMO scheme aligning statutory survey windows, implemented by ROs.
Hellenic Register of Shipping: HRS, Greek classification society, recognized organization for Greece.
Hold Loading: per-hold cargo mass limit derived under IACS UR-S22 for bulk carriers.
Hull Girder Ultimate Strength: limit-state capacity assessed under IACS Rec.78 and CSR-H.
Hull Monitoring System (HMS): optional class notation for installed hull strain and motion monitoring.

I

IACS: International Association of Classification Societies, 12 members.
IACS Charter: governance document setting IACS membership criteria and obligations.
IACS Council: highest decision-making body of IACS comprising one representative per member.
IACS GPG: General Policy Group, IACS senior management body subordinate to Council.
IACS Member: Classification society belonging to International Association of Classification Societies.
IACS Rec.142: cyber resilience recommended practice, predecessor guidance to UR-E26 and UR-E27.
IACS Rec.34: Standard Wave Data, North Atlantic scatter diagram used in direct strength calculations.
IACS Rec.78: Hull Girder Ultimate Strength procedures and acceptance criteria.
IACS Recommendation (Rec.): non-binding guidance issued by IACS technical panels.
IACS Unified Interpretation (UI): agreed interpretation of an IMO instrument applied uniformly by members.
IACS Unified Requirement (UR): minimum technical requirement mandatorily adopted by all IACS members.
IBS: Lloyd's Register Integrated Bridge System notation.
Icebreaker6: Russian Maritime Register icebreaker category, lightest icebreaker class.
Icebreaker7: RS icebreaker category for medium-duty icebreakers.
Icebreaker8: RS icebreaker category for heavy icebreakers operating year-round.
Icebreaker9: RS highest icebreaker category for nuclear and heaviest diesel-electric icebreakers.
In Class: status indicating the vessel is currently maintained to the society's rules without overdue items.
In Water Survey (IWS): Class accepted survey of underwater hull performed afloat by divers.
Indian Register of Shipping (IRS): IACS member since 2010, headquartered Mumbai.
Intermediate Survey (IS): Class survey held between second and third anniversaries of class certificate.
ISM Code: International Safety Management Code, mandatory under SOLAS IX.

J

JBP: IACS Joint Bulker Project, the development project that produced CSR-BC.
JTP: IACS Joint Tanker Project, the development project that produced CSR-OT.

K

Korean Register (KR): IACS member since 1988, headquartered Busan.

L

LCS: Lashing Computer System notation issued by DNV and others for container securing software.
Lloyd's Register (LR): classification society founded 1760, IACS founding member, headquartered London.
LMC: Lloyd's Register Machinery Class notation for machinery built and installed under LR survey.
Loadicator: Approved onboard cargo planning and stress calculation software.
Loading Manual: class-approved document defining permissible cargo and ballast distributions.
Longitudinal Strength: hull-girder bending and shear capacity, governed by IACS UR-S11 and CSR-H Part 1 Chapter 5.
LR 100A1: Lloyd's Register principal class notation for ships built and maintained to LR Rules for unrestricted service.
LR ECO: LR environmental descriptive notation.
LR ESP: LR notation for ships entered under the Enhanced Survey Programme.
LR IBS: Integrated Bridge System notation.
LR IWS: LR In-Water Survey notation.
LR LMC: LR Machinery Class.
LR ShipRight: LR's direct calculation and design assessment procedures.
LR UMS: LR Unattended Machinery Space notation.

M

Machinery Survey: periodical survey of propulsion, auxiliary and electrical machinery.
Major Conversion: structural alteration triggering re-application of current rules per SOLAS and class.
Material and Welding Requirements: IACS UR-W series defining materials, welding consumables and procedures.
MNS-star: ClassNK notation for machinery built under NK survey with star indicating full survey attendance.
MSC.215(82): IMO Performance Standard for Protective Coatings (PSPC).
MSC.219(82): IMO resolution adopting CSR for bulk carriers and oil tankers into SOLAS through Chapter II-1.

N

NAUT-OSV: DNV navigation notation for offshore support vessels.
Newbuilding Survey: surveys during construction culminating in delivery and assignment of class.
NK: Nippon Kaiji Kyokai, ClassNK, IACS member headquartered in Tokyo.
NK NS-star: ClassNK principal hull notation for vessels built under NK survey with star indicating full attendance.
Notation Modifier: descriptor appended to a class notation indicating scope, service or limitation.

O

Occasional Survey: Class survey arranged outside scheduled cycle for damage or modifications.
Operational Limitations: restrictions on service area, draft or speed recorded in the class certificate.

P

PC1: IACS Polar Class for year-round operation in all polar waters, including multi-year ice.
PC2: IACS Polar Class for year-round operation in moderate multi-year ice conditions.
PC3: IACS Polar Class for year-round operation in second-year ice with multi-year inclusions.
PC4: IACS Polar Class for year-round operation in thick first-year ice with old ice inclusions.
PC5: IACS Polar Class for year-round operation in medium first-year ice with old ice inclusions.
PC6: IACS Polar Class for summer and autumn operation in medium first-year ice.
PC7: IACS Polar Class for summer and autumn operation in thin first-year ice.
Periodic Survey: General term for scheduled class or statutory surveys.
Polar Class Notation: IACS notation PC1 to PC7 defined under UR-I for polar operation.
Polish Register of Shipping (PRS): IACS member, headquartered Gdansk.
Pre-Class Survey: class assessment of ships transferring class under TOCA procedures.
Provisional Certificate of Class: short-validity class certificate issued at delivery pending issue of the full certificate.
PSPC: Performance Standard for Protective Coatings adopted by IMO resolution MSC.215(82).
PSPC-WBT: PSPC for water ballast tanks under MSC.215(82).

Q

Quality System Certification Scheme (QSCS): IACS scheme for accreditation of member quality management systems.

R

Recognized Organization (RO): Class society or other entity acting on behalf of the flag state.
Recognized Security Organization (RSO): Performs port-facility security tasks under ISPS Code.
Renewal Survey: Survey at intervals not exceeding five years.
Repair Survey: Class survey covering repairs to damaged or wasted structure.
RINA: Royal Institution of Naval Architects, London, founded 1860.
RINA C HULL MACH: RINA main class symbol for hull and machinery surveyed under RINA Rules.
Russian Maritime Register of Shipping (RS): IACS founding member, headquartered St Petersburg.

S

SafeHull: ABS dynamic loading-based design and assessment system applied to tankers and bulk carriers.
Scantlings: hull structural dimensions assessed against IACS URs and CSR formulae.
Section Modulus: hull girder property governed by IACS UR-S11 minima.
SH: ABS SafeHull notation.
Shipyard Approval: class approval of shipyard quality system and welding procedures.
SMC: Safety Management Certificate issued to the ship under the ISM Code by RO on flag behalf.
SOLAS II-1: chapter governing construction, subdivision and machinery; basis for many class-statutory interfaces.
SOLAS II-2: chapter on fire safety, verified by RO during construction and periodical surveys.
SOLAS V/19: Carriage requirements for navigational equipment.
Special Survey (SS): 5-yearly class survey.
Statutory Certification: certification under IMO conventions issued by ROs under flag agreement.
Stowage Approval: class approval of cargo securing arrangements and lashing plans.
Survey Status Report: document summarising outstanding surveys and conditions of class.
Suspension of class: Temporary withdrawal of class status, often resulting in suspension of statutory certificates.

T

Tailshaft Survey: periodic propulsion shaft survey under CMS or extended interval arrangements.
TM (Thickness Measurement): ultrasonic gauging of plate and stiffener thickness at renewal survey.
TOCA: IACS Transfer of Class Agreement governing class change between IACS members.

U

UMS: Unattended Machinery Space class notation.
UR-E: IACS UR series covering electrical and automation requirements.
UR-E22: IACS UR on the onboard use of computer based systems.
UR-E26: IACS UR on Cyber Resilience of Ships, in force for vessels contracted on or after 1 July 2024.
UR-E27: IACS UR on Cyber Resilience of On-board Systems and Equipment, in force from 1 July 2024.
UR-I: IACS UR series for Polar Class, defining PC1 through PC7.
UR-I1: IACS UR defining Polar Class descriptions.
UR-I2: IACS UR on Polar Class structural requirements.
UR-I3: IACS UR on Polar Class machinery requirements.
UR-M: IACS UR series on machinery.
UR-M53: IACS UR on calculation of crankshafts for I.C. engines.
UR-M68: IACS UR on dimensions of propulsion shafts.
UR-S: IACS UR series on strength of ships.
UR-S1: IACS UR on longitudinal strength of ships carrying liquids in bulk, applied to oil tankers.
UR-S11: IACS UR on longitudinal strength standard, defining minimum section modulus and bending moments.
UR-S11A: IACS UR on longitudinal strength standard for container ships under CSR-aligned methodology.
UR-S17: IACS UR on evaluation of allowable hold loading on bulk carriers with one hold flooded (rules for existing ships).
UR-S18: IACS UR on the evaluation of scantlings of corrugated transverse watertight bulkheads in bulk carriers considering hold flooding.
UR-S19: IACS UR on evaluation of scantlings of the transverse watertight corrugated bulkhead between cargo holds Nos.1 and 2 with cargo hold No.1 flooded for existing bulk carriers.
UR-S20: IACS UR on evaluation of allowable hold loading on bulk carriers considering hold flooding (existing ships).
UR-S21: IACS UR on evaluation of scantlings of hatch covers and coamings of cargo holds of bulk carriers.
UR-S22: IACS UR on evaluation of allowable hold loading of cargo holds of bulk carriers considering hold flooding.
UR-S25: IACS UR on longitudinal strength standard for general dry cargo ships.
UR-S6: IACS UR on use of steel grades for various hull members.
UR-W: IACS UR series on materials and welding.
UR-W11: IACS UR on normal and higher strength hull structural steels.
UR-W14: IACS UR on steel forgings.
UR-W17: IACS UR on approval of consumables for welding.
UR-Z: IACS UR series on survey and certification.
UR-Z10.1: IACS UR on hull surveys of oil tankers, the foundation of tanker ESP.
UR-Z10.2: IACS UR on hull surveys of bulk carriers, the foundation of bulk carrier ESP.
UR-Z10.5: IACS UR on hull surveys of double hull oil tankers.

V

Verification of compliance: Mandatory function under the III Code requiring IMO audit of Member States.
Voyage Restriction: limitation imposed by class on geographic service, recorded on the certificate.

W

WBT: water ballast tank, subject to PSPC under MSC.215(82) and ESP close-up survey under UR-Z10.
Withdrawal of class: See class withdrawal.
Working Stress Design: scantling philosophy used in pre-CSR rules, superseded by partial safety factors in CSR-H.

X

X-Notation: society-specific marker, for example RINA's X prefix on optional descriptive notations.

Y

Yard Approval: classification society recognition of a shipbuilder's quality and welding systems.
Yearly Survey: colloquial term for the Annual Survey.

Z

Z-Series: IACS UR-Z series covering survey, certification and class transfer requirements.
Zonal Approach: corrosion margin methodology used in CSR-H assigning net scantlings to defined ship zones.