I think the term "source available" is somewhat ambiguous, in it can potentially refer to a few different arrangements:
1) The source is freely available to anyone to view, but rights to compile/modify/redistribute/etc are heavily restricted
2) Proprietary software you have to purchase, but it comes with the full source code
3) Proprietary software sold in binary form, but where the full source code can be licensed for an additional fee
4) Proprietary software sold in binary form, but where customers can acquire source code access subject to heavy restrictions
As an example of option (4) – there was a period in the past when IBM used to allow customers to order the source code to some of its mainframe software products (including the MVS operating system), but it was only shipped on microfiche. As such customers could view the source code but not compile or modify it. Additionally, much of that software was written in a proprietary dialect of PL/I known as PL/S (or later versions are called PL/X), for which IBM mostly refused to release the compiler – so even if you transcribed the microfiche into machine readable format, you didn't have a compiler with. (IBM has occasionally licensed the PL/S compiler to ISVs and other partners; some clone mainframe vendors, such as Fujitsu, apparently built compilers for PL/S by extending PL/I compilers; RAND Corporation did something similar in the 1980s, and briefly distributed the result, but got in trouble with IBM's lawyers and had to stop.)
XNU is closest to sense (1), but rather than being "heavily restricted", it is almost Open Source Definition compliant – there is an additional restriction which violates the Open Source Definition, but for many users that additional restriction will have no practical relevance. It is certainly a long way from a "reference license" which lets you read the source code but not compile or modify it or distribute your changes.
None of this conflicts with what the parent said. The term isn't ambiguous any more than the word "source" is ambiguous because it doesn't specify a language. It means exactly what both you and the parent said. It unambiguously defines a class rather than an instance, and disambiguates vs open source, and all these example class members you provided fall within the idea the parent expressed.
I think the point c3534l was making is that open source should be considered a generic term and should not have its meaning conflated with Open Source™ which is just one group with one opinion.
And I agree, at least in part. I think the agonising over a precise definition of open source is as futile as the attempts to distinguish "hacker" from "cracker" twenty years ago. At the same time I also agree that proprietary software that has available source but no rights to do anything with it is most definitely not open source by any rational definition.
So whether or not OpenDarwin is Open Source™, it's still open source.
I fully understood his point and at the same time disagree with it - "open source" should not be considered a generic term, and the reasons are purely practical. OSI has taken this term two decades ago and coined its widely known meaning, where "open source" means "compliant with the OSI open source definition", just as GNU did with "free" or "libre" software.
The terms "open source" and "free software" have become ubiquitous in the programming world and widespread even in popular culture and redefining them brings completely no benefit - not even cultural ones, since the terms "open" or "free" or "libre" software do not have background associated with racism or sexism, unlike some of the recent nomenclature debates.
And this "one group with one opinion" that you are speaking of has been one of the most powerful software groups in the world with a lot of influence on how the programming world is shaped and what software you, your family, your employers, your friends and your enemies use in your daily life, so your argument about it being "one group with one opinion" holds as much sense to me as Microsoft being "just one operating system vendor with one opinion" in a discussion about operating systems.
I simply disagree that the group which coins a term gets to control its usage or its colloquial definition. That's not a reflection of my preference, it's just my own observation of reality. In reality, words mean whatever the recipient thinks it means. In practice, that means the assumptions of the median person overrule any formal definition.
They didn't write a law for the purpose of oppression and human farming. They presented a suggestion for everyone's benefit and sanity, and everyone adopted it voluntarily because it was beneficial and sane.
I'm not arguing for benefits or sanity. I'm not claiming it's a good outcome, or that it's an outcome I prefer. Far from it—I wish it was as you describe. I wish we didn't have to keep inventing new words as existing ones get corrupted by improper use.
> I think the point c3534l was making is that open source should be considered a generic term and should not have its meaning conflated with Open Source™ which is just one group with one opinion.
They're both "just one group with one opinion." The difference is that one is definition widely accepted as a term of art in software development and the other is not.
You mean the term "source available", which has been a well-defined term for years as well.