{{Short description|Method of designating a version of a product}} {{more citations needed|date=July 2013}} [[File:FordMondeoMk2Mk3.jpg|thumb|Two Ford Mondeo sedans, a Mk II (grey, left) and a Mk III (blue, right)]] The word '''''mark''''', followed by number, is a method of designating a version of a product. It is often abbreviated as '''Mk''' or '''M'''. This use of the word possibly originates from the use of physical marks made to measure height or progress. Furthermore, by metonymy the word mark is used to note a defined level of development or a model number.
The kind of products that use this convention vary widely in complexity. The concept shares some similarities with the ''type'' designation (in hardware), also called ''software versioning'': 1.0+ (1.1, 1.12, 2.0, 3.0, etc.), used to designate general software product releases, and other version control schemas. Thus designations like "Mark I", "Mark II", "Mark III", "Mark IV", etc. come to be used as proper names for persons and products.
==Application == ''Mark'' refers to a mark on the modification plate of a system, component or machine. Modification plates are used to identify which modifications have already been applied to the device, either at the factory or by maintainers. The use of Mark as a method of versioning has entered common usage however, and may be applied to devices without a modification plate to physically mark.
===United Kingdom=== In British military practice, Mark ("Mk") designations were given in Roman numerals<ref>{{cite book |last1=Dunlap |first1=Roy F. |title=Ordnance Went Up Front |date=1948 |publisher=Small-Arms Technical Publishing Company |page=139}}</ref> (replaced by Arabic numerals in 1944<ref>{{cite book |last1=Clarizia |first1=Vincenzo |title=Ancient Weapons of Oman: Volume 2 - Firearms |date=11 August 2022 |publisher=Archaeopress Publishing Ltd in association with the Ministry of Heritage and Tourism |isbn=9781803270333 |page=98}}</ref><ref name="nhhcsmle">{{cite web |title=British SMLE Rifle |url=https://www.history.navy.mil/our-collections/artifacts/arms-and-ordnance/small-arms/long-arms0/british-smle-rifle.html |website=Naval History and Heritage Command |access-date=17 May 2026 |date=29 April 2024}}</ref>) to reflect variants of or production changes to service weaponry, either on their own or as part of numerical ("No.") designations; in the Lee-Enfield rifle series for example, the SMLE rifles were produced to Mk I, Mk III, and Mk V specification (with the latter two later gaining a numerical designation of "No. 1 Mk III/Mk V Rifle"), while the No .4 rifles were produced to No. 4 Mk I and No. 4 Mk 2 specification. Variations or production changes could be further denoted with an asterix<ref>{{cite book |last1=Rottman |first1=Gordon L. |title=Korean War Order of Battle: United States, United Nations, and Communist Ground, Naval, and Air Forces, 1950-1953 |date=2002 |publisher=Greenwood Publishing Group |isbn=0275978354 |page=195}}</ref> as with the SMLE Mk III* (later "No. 1 Mk III*")<ref name="nhhcsmle" /> and No. 4 Mk I*. The British Army switched to Land Service number designations ("LXA1/A2/A3/etc.") in 1954,<ref>{{cite book |last1=Laidler |first1=Peter |last2=Edmiston |first2=James |last3=Howroyd |first3=Davd |title=A History of the Small Arms made by the Sterling Armament Company |date=7 August 2020 |publisher=Pen & Sword Military |location=Barnsley |isbn=9781526773302 |pages=86–87}}</ref> but legacy items{{Efn|Including but not limited to the No. 4 Rifle,<ref name=80sccf>{{cite book|author=Ministry of Defence (United Kingdom)|title = Army Code No. 71295, Cadet Training Manual (CCF Army Sections)|year= 1982}}</ref> the various Sten machine carbines,<ref>{{cite book |title=WO Code No. 8948, Infantry Training Volume I, Pamphlet No. 4 The Sub-Machine Gun (All Arms) (Amended April 1957) |date=21 November 1955 |publisher=War Office}}</ref> the original .303 versions of the Bren gun,<ref name=80sccf /> the No. 5 Mk 1 Bayonet,<ref>{{cite book |last1=Laidler |first1=Peter |last2=Edmiston |first2=James |last3=Howroyd |first3=David |title=A History of the Small Arms made by the Sterling Armament Company |date=7 August 2020 |publisher=Pen & Sword Military |location=Barnsley |isbn=9781526773302 |chapter=Chapter Sixteen, Accessories and Ancillaries |pages=286–290}}</ref> the No. 8 Mk 1 0.22in Rifle,<ref name=no8rifle1>{{cite book|author=War Office |title = WO Code No. 13217, User Handbook for the Rifle, 0.22in., No. 8, Mk. 1|year= 1961}}</ref><ref name=no8rifle2>{{cite book|author=Ministry of Defence (United Kingdom) |title = Army Code No. 13217, User Handbook for the Rifle, 0.22in, No 8, Mk 1 and Rifle, Aiming, 0.22in L2A1|year= 1970}}</ref><ref name=hansardrifles>{{Cite hansard|url=https://hansard.parliament.uk/Lords/2000-03-30/debates/2c4fae55-2cff-4b05-8e1f-a528b846c8f8/ArmedForcesRifles|title=Armed Forces' Rifles |date=30 March 2000|house=House of Lords}}</ref><ref name=cadetforcemanual>{{cite book|author=Ministry of Defence (United Kingdom) |title = Army Code No. 14233, The Army Cadet Force Manual|year= 2005}}</ref> the No. 36M Mk 1 HE Hand Grenade,<ref>{{cite book |title=WO Code No. 9941, Infantry Training Volume 1, Pamphlet No. 7 Grenades (All Arms) |date=March 1964 |publisher=War Office |pages=1-8, 48}}</ref> the No. 80 Mk 1 White Phosphorus Smoke Hand Grenade,<ref>{{cite book |title=WO Code No. 9941, Infantry Training Volume 1, Pamphlet No. 7 Grenades (All Arms) |date=March 1964 |publisher=War Office |pages=18-23}}</ref><ref name=1975gren>{{cite book|author=Ministry of Defence (United Kingdom) |title = Army Code No. 71001, Infantry Training Volume III, Pamphlet No. 13 Grenades|date=May 1975}}</ref><ref name=oct1995gren>{{cite book |title=Army Code No. 71001, Infantry Training Volume III, Pamphlet No. 13 Grenades and Associated Weapons |date=October 1995 |publisher=Ministry of Defence (United Kingdom)}}</ref> the No. 1 6 Inch Beehive Demolition Charge,<ref>{{cite web |title="Beehive" Charge Demolition No1 6in Inert Mk6 |url=https://www.iwm.org.uk/collections/item/object/30021843 |website=Imperial War Museum |access-date=14 January 2026}}</ref><ref name=hansard>{{Cite hansard|url=https://hansard.parliament.uk/commons/1993-07-26/debates/e070a3bc-3123-48e9-b578-faef727deeb5/SennybridgeRange|title=Sennybridge Range |date= 26 July 1993|house=House of Commons}}</ref><ref>{{Cite web |author = Mondial Defence Systems |url=http://www.mondial-defence.com/images/PDF_Data_Sheets/Beehive_Demolition_Charge.pdf |title=Beehive Charge Mk.6 |access-date=2020-06-12 |url-status=dead |archive-url=https://web.archive.org/web/20100928153854/http://www.mondial-defence.com/images/PDF_Data_Sheets/Beehive_Demolition_Charge.pdf |archive-date=2010-09-28 }}</ref><ref>{{cite web |author1=Chemring Energetics UK |author1-link=Chemring Group |title=Charge Demolition No.1 6 inch Beehive |url=http://www.chemringenergetics.co.uk/~/media/Files/C/Chemring-Energetics-V2/documents/Datasheets%200216/Beehive%20Feb%2016%202pp.pdf |access-date=12 June 2020 |archive-url=https://web.archive.org/web/20180619073616/http://www.chemringenergetics.co.uk/~/media/Files/C/Chemring-Energetics-V2/documents/Datasheets%200216/Beehive%20Feb%2016%202pp.pdf |archive-date=19 June 2018 |date=February 2016 |url-status=dead}}</ref><ref>{{cite web |title=Beehive Charge Demolition No 1 6in (sectioned) |url=https://www.iwm.org.uk/collections/item/object/30020697 |publisher=Imperial War Museum |access-date=9 April 2022}}</ref><ref name="chemringdemstores">{{cite web |author1=Chemring Energetics UK |author1-link=Chemring Group |title=A Leading Provider of Energetic Materials |url=https://www.chemring.co.uk/~/media/Files/C/Chemring-V3/publications/CEUK%20Brochures/Chemring_Energetics%20UK_Dem%20Stores_Iss1_Final.pdf |access-date=9 April 2022 |date=October 2016}}</ref> the No. 14 Mk 1 11 lb Hayrick Demolition Charge,<ref>{{Cite web |author = Mondial Defence Systems |url=http://www.mondial-defence.com/images/PDF_Data_Sheets/Hayrick_Charge.pdf |title=Charge Demolition No. 14 Mk 1 |access-date=2020-06-04 |url-status=dead |archive-url=https://web.archive.org/web/20140123210020/http://www.mondial-defence.com/images/PDF_Data_Sheets/Hayrick_Charge.pdf |archive-date=2014-01-23 }}</ref><ref name=necklacecharges>{{cite web |author = Mondial Defence Systems |title=Charge Demolition Necklace L1A1 |url=http://www.mondial-defence.com/images/PDF_Data_Sheets/Hayrick%20Charge%20Demolition%20No.14.pdf |access-date=31 May 2020 |archive-url=https://web.archive.org/web/20140123210015/http://www.mondial-defence.com/images/PDF_Data_Sheets/Hayrick%20Charge%20Demolition%20No.14.pdf |archive-date=2014-01-23 |url-status=dead}}</ref> and the No. 1 Mk 3 Pyrotechnic Pistol Signal Kit.<ref name=bulletpointjan2012>{{cite magazine |title=Bullet Points |url=https://soldier.army.mod.uk/media/yhncbqka/soldier-jan-2012.pdf#page=65 |magazine=Soldier Magazine |publisher=British Army |access-date=15 November 2025 |page=65 |date=January 2012}}</ref>}} continued to be referred to by their Mk designations until their replacement by newer equipment.<ref>{{cite book |last1=Gander |first1=Terry |title=Encyclopaedia of the Modern British Army |date=20 October 1986 |publisher=Book Club Associates by arrangement with Patrick Stephens Limited |isbn=085059684X |pages=99-100 |edition=3rd}}</ref> To this day, there are stores using an Mk designation that are still in service such as the No. 1 Mk 4 Protective Suit.<ref>{{cite web |title=Smock, Protective NBC Suit, No.1, Mk. IV: British Army |url=https://www.iwm.org.uk/collections/item/object/30016312 |website=Imperial War Museum |access-date=11 January 2026}}</ref>
British railway coaching stock has been referred to using Arabic numeral marks following the introduction of the British Railways Mark 1 in 1951, with further designs being referred to as the Mark 2 (introduced in 1964), the Mark 3 (introduced in 1975), and the Mark 4 (introduced in 1989). The Mark 5 designation was initially intended for coaches belonging to the 1990 InterCity 250 project, but this was cancelled in 1992; the designation was later applied to CAF-built coaches used on the ''Caledonian Sleeper'' service since 2019, replacing earlier Mark 2 and Mark 3 coaches, while coaches built by the same manufacturer for TransPennine Express are referred to as the Mark 5A.
===United States Navy=== The United States Navy uses the terms "Mark" and "Mod" as a method to uniquely designate specific types and configurations of equipment that would otherwise lack military designations. The practice was adopted by the Naval Ordnance group in 1944, and was formalized in the MIL-STD-1661 MARK and MOD Nomenclature System<ref>{{cite web |last = MIL-STD-1661 |title= Mark and Mod Nomenclature System |date = 1978-08-01 |access-date = 2022-12-13 |url = http://quicksearch.dla.mil/qsDocDetails.aspx?ident_number=37053}}</ref> <ref name="copy of mil-std-1661">{{cite web |title=MIL-STD-1661 (OS) 1 August 1978 MARK and MOD Nomenclature System |url=https://quicksearch.dla.mil/Transient/9D07108405FB4616BF895A53D79DBA35.pdf |website=Defense Logistics Agency |access-date=12 December 2022 |archive-url=https://web.archive.org/web/20221213054724/https://quicksearch.dla.mil/Transient/9D07108405FB4616BF895A53D79DBA35.pdf |archive-date=13 December 2022 |date=1 August 1978|url-status=live}}</ref> in 1978. As the system came from the Ordnance group, it is primarily used to describe naval guns, gun mounts, and other similar weapon systems.
==Examples==
===Military===
*Mark I, the first British Army tank design to see service *Mk 2 grenade (an American grenade used in World War II, Korean War and the Vietnam War) *Mark III, Merkava main battle tank (Israel Defense Forces) *Mark 4 aerial atomic bomb, several United States atomic gravity bombs employed a Mark-# scheme (USAF) *A.T. Mine G.S. Mark V an anti-tank mine of the WWII British Army *Mk 6 Assault Boat (British Army) *Mark 7 nuclear bomb *Tank, Cruiser, Mk VIII - eighth in series of British Army cruiser tanks *Mk 11 Sniper Weapon System (US Armed Forces) *Mark 12 Mod X Special Purpose Rifle (US Special Operations Forces) *Mk 13 missile launcher (anti-ship/anti-aircraft) (US Navy) *Mark 14 Mod 0 Enhanced Battle Rifle (US Armed Forces) *Mk 16 SCAR-L and Mk 17 SCAR-H assault rifle and battle rifle commissioned by the US armed forces *Mk 18 CQBR M4A1 Receiver upgrade (US Armed Forces) *Mk 19 grenade launcher (US Armed Forces) *Mark 48 torpedo as well as other torpedoes used by the British and US Navies
===Vehicles=== thumb|VW Golf Mk III * The AC Cars Cobra — MkI, MkII and MkIII * The Ford GT40 series — MkI, MkII, MkIII and MkIV * Various Jaguar Cars — Jaguar Mark 2, Jaguar Mark IV, Jaguar Mark X, etc. * The Lincoln Mark series - Continental Mark II, Lincoln Mark VIII, etc. * Various Lola Cars - Mk.4, Mk.5, Mk.6 * Various Toyota vehicles, especially the MR2 — MkI, MkII, MkIII * Volkswagen Golf automobile — Mk1, Mk2, Mk3, Mk4, Mk5, Mk6, Mk7, Mk8 * British Rail Coaches — Mark 1, Mark 4, etc. * The Walt Disney World Monorails - Mark IV and Mark VI.
===Musical and photo instruments=== * Rhodes piano — Mark I, Mark II * Mesa Boogie Mark Series — guitar amplifiers, Mark I to Mark V * Telharmonium, an early electronic musical instrument, Mark I to III * SELMER Saxophones — Mark VI and Mark VII Series of saxophones * Elektron music machines — Mk II versions of the Monomachine synthesizer and the Machinedrum drum machine * Canon EOS-1D series — 1Ds Mk II, 1D Mk III, 1Ds Mk III, etc.
===Firearms=== thumb| Ruger Mk I at top; Ruger Mk II; Ruger Mk IV Hunter. demonstrates the use of the designation as the name, often referred to simply as "the Mk II", "a Mk III", etc. * Ruger Standard series (Ruger MK I, Ruger MK II, Ruger MK III) * Weatherby Mark V
===Electronics=== * Harvard Mark I, Mark II, Mark III, and Mark IV, early computers designed by Howard Aiken at Harvard University from 1937 to 1952 * Navigation system on BMW cars - Mk I, Mk II, Mk III and Mk IV
===Medical research=== * The term SARS‑CoV‑2 for the novel Coronavirus may be considered part of this designating method. The term COVID-19 has been misinterpreted in this way on several occasions; the number here, however, denotes the year of the first appearance of the virus, 2019.
==See also== {{div col|colwidth=22em}} *British military aircraft designation systems *Army Nomenclature System *Mark I *Mark II *Mark III *Mark IV *Mark V *Mark VI *Mark VII *Mark VIII *Mark IX *Mark X *Mark XI *Mark XII *Mark XIII *Mark XIV *Mark XV *Mark XVI *Mark XVII *Mark XVIII *Mark XIX *Model *Type (designation) {{div col end}}
==Notes== {{Notelist}}{{reflist|group=note}}
== References == {{Reflist}}
==External links== {{wiktionary}} * [http://www.designation-systems.net/usmilav/miscsystems.html Miscellaneous designation systems]
Category:Technical terminology