I have seen many examples, Harvard Mark 1, Manchester Mark 1, Colossus Mark 1 and 2. It is possible that this is a very obvious thing for native English speakers, but not entirely for me. Was this an old custom? Who started it? Why did it not continue afterwards?


Was this an old custom?

By now, this word has fallen into disuse, or it has at least fallen out of vogue. In the context of computing at least, the word Mark followed by a Roman (or sometimes Arabic) numeral has fallen into disuse as a versioning scheme. And given the word's many uses and meanings, it's not surprising that this use is unfamiliar to you.

But "mark" really is just another word for "version", or "revision".

Who started it? Why it did not continue afterwards?

For the answer to these questions, better see the link https://english.stackexchange.com/questions/83548/mark-in-generational-naming-of-products

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    "By now, this word has fallen into disuse, or it has at least fallen out of vogue." – Has it? I see it all over the place. In fact, the company I work for has just this week introduced Mk III of one of our products. Also, the phrase "Mk I Eyeball" seems to be common enough to be known even to me who is not a native speaker. Apr 12 '18 at 8:55
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    @JörgWMittag - indeed, it's still commonly used in many contexts. For instance, I have a Ford Focus "Mark 2.5" sitting outside ... it's only really computer manufacturers that have abandoned the word.
    – Jules
    Apr 12 '18 at 9:07
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    Canon uses Mk# for all their follow up camera models and I have seen lot of mk# versions of things.
    – PlasmaHH
    Apr 12 '18 at 10:38
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    It's really not correct to say this use of "Mark" has fallen out of vogue. In my estimation it's about as prevalent as it has always been. It is and was used primarily for specialist and custom-built technology and is common in science fiction (e.g. Iron Man Mark 42 or Mjolnir Mk. VI). en.wikipedia.org/wiki/Mark_(designation) Apr 12 '18 at 13:56
  • In Iron Man 3, there was a lot that revolved around the Mark 42 Iron Man suit. Apr 13 '18 at 1:09

As mentioned in the comments, “Mark” here is used in a similar sense to “version”. The name of the computer is the first word in the designation (“Harvard”, “Manchester”, “Colossus”); then follows the version, or revision — “Harvard Mark 1” is the first Harvard computer, etc. Note that in some cases this designation is used even though there was no “Mark 2” (or “Mark II”): for example, the Manchester Mark 1 was followed by the Ferranti Mark 1. In some cases, the “Manchester Mark 1”-style name wasn’t the official name (the Manchester Mark 1 was the Manchester Automatic Digital Machine), but computers were so rare at the time this naming practice was common that people simply referred to computers by their location.

The practice of using “Mark” to identify computer revisions didn’t last long, and you’ve listed most of the models which are remembered in this way; I get the impression this was only used in the 1940s.

This terminology is also commonly used, at least in the United Kingdom, for car models and aircraft; for example, the Ford Escort, the Volkswagen Golf, the Spitfire...

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    In some contexts, "mark" is spelled "-". Apr 13 '18 at 13:08
  • It was also widely used for aircraft. For example, the Spitfire started at Mk.I and ended up at Mk.XXIV; the Hurricane existed as Mk.I through Mk.V, with Canadian-built versions designated Mk.X--Mk,XII (and various "sub-marks", such as the Mk.IIA through IIE). Apr 13 '18 at 14:32
  • @DavidRicherby ...and this later led to its use on Science Fiction. Example: Battlestar Galactica's Viper Mark IV
    – xDaizu
    Apr 16 '18 at 14:14

It's basicly a variant designation. The custom is originated with English military and describes a variant of some equipment as marking for (often) otherwise not distinguished items. As many other conventions it did spread from military use over to civilian engineering, like with railroad manufacturers naming improved wagoons as Mk2/3/4... In the mid 20th century it reached adbertisement and official naming, with a 'feeling' much like todays version numbering hype - like eating 2.0, Industry 4.0 and so on.

Modern day equivalent (as used in the US) would be 'Model'.

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    It may be worth noting that Mk is short for Mark.
    – OmarL
    Apr 12 '18 at 7:55
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    Also, keep in mind that many early computer projects had a military background.... Apr 12 '18 at 11:07
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    Unsure it worth mentioning as it's mostly an anecdote for the subject but one 'famous' use is Iron Man Armors naming which Tony Stark refer to as Mark 1 to Mark 54 (Unsure of the top numbering) for the version of construction of his armor. (Stark coming from a military weapon dealer background this sounds logical for me :))
    – Tensibai
    Apr 12 '18 at 11:57
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    @rackandboneman Exactly. Colossus was military hardware. Apr 12 '18 at 14:48
  • Likewise the most common torpedoes carried by the US Navy are the Mark 48 and Mark 54 (the Mark 1 goes back to the late 19th century).
    – hobbs
    Apr 13 '18 at 6:10