This is not correct.

It's true that the words "open" and "source" were occasionally combined previously to express a variety of different concepts related to software, and the term "open source" as such also existed to describe a kind of "intelligence information" that was drawn entirely from open sources like newspapers rather than closed sources like wiretaps. But that's entirely different from the term being in usage with a well-defined meaning.

In this particular case, it's relevant that OpenDOS was never "open source" in the sense coined by Chris Peterson. Caldera was trying to see if they could get the benefits of free software without paying the costs (loss of control and revenue) by making DR-DOS what we would now call "source available", so they promoted what they called an "open source code model". This phrase doesn't make sense if you parse it as "open-source code-model"; there's no such thing as a "code model" in any context related to software. Rather, they intended it to parse as "open source-code model". So "open source" wasn't even a phrase in this case until Adam shortened "open source code" to "open source" for the subject of his email.

Caldera's attempt to promote the idea of an open source-code model, as distinct from "free software", failed, though I probably did download a copy of OpenDOS at the time. People didn't go around talking about the advantages and disadvantages of "open source" or even the "open source-code model". It just wasn't a thing.

Later in the thread, you point out https://groups.google.com/g/comp.os.ms-windows.programmer.wi..., from 01993, three years earlier, where one Jerome Schneider says, "Open Source is best for everyone in the
long run," but is not talking about a social movement, just about source code being open (in the sense of published) rather than secret. None of the six replies refer to "open source", and apparently nobody used the term for three years, at which point it occurred as the grammatical adjacency coincidence you're pointing at, and then apparently nobody used it for two more years.

The OSI did not coin "open source", as the OSI didn't exist at the time; Chris Peterson did, in a meeting of free-software people who were trying to figure out how to persuade more companies to do what Netscape was doing and release their software as free software. The next day, Eric Raymond sent out the email I mentioned, and updated his home page to replace "free software" with "open source". That's the day the term came into existence. I think it took a few weeks to hammer out the OSD and organize the OSI.

I was on the fsb ("free software business") mailing list at the time, where we constantly talked about the issues of how to build businesses on free software. (Maybe that's why Eric Cced me on the email; I certainly wasn't the same kind of luminary as the other people on the list.) The term "open source" just wasn't a term that we were using. Debian wasn't using the term. On FoRK we weren't using the term --- I wasn't on FoRK in 01996 but I was in 01998 http://web.archive.org/web/20080517045124/http://xent.com/Fo....

It's true that if you go looking through a large enough corpus of historical documents looking for a coincidence of two common words, you will find occurrences. There are occurrences of the term "internetted" documented from 01874, for example. It's surprising that in the 25 years of Usenet and mailing lists prior to 01998 you've only been able to find two coincidences out of the hundreds of millions of public messages posted by tens of millions of people; surely there are five or six more in there at least.

I'm answering you at such length in part because I've seen you to be a reasonable person at times in the past; I did read your dissertation, after all, and learned some things from it.

Please don't disappoint me by continuing to advocate the same clearly false position. You have enough information now that persisting in your error would amount to reckless disregard for the truth, and therefore malicious slander against the people whose reputations your falsehoods tend to damage.