> That is what you say, though objectively, legally and protectively, it
> is not the reality.

Legally and protectively "free software" doesn't have more meaning or value
than "open source". Possibly less.

That said, as I mentioned, the term "open source" is used by government
agencies. It also appears in Italian legislation (translated in Italian,
even though developers usually say "open source", without translating it).
The term "open source" has also been used in court decisions with the
correct meaning in the United States, as well as at least one court order
in Italy I am aware of (which didn't translate it).

That said, the mere fact that it is not *illegal* to use the term "open
source" as a synonym of "source available" doesn't mean it's correct.

You made a claim that that particular piece of software is open source. I
said the claim is wrong. For that to be the case, "open source" doesn't
need to be a trademark and calling that piece of software "open source"
doesn't need to be illegal. You are moving the goalpost to something I
never said.

> The term "open source" is used in vague manner all over the world in
> various applications including those which are not software. And by my
> previous example it is used in case of proprietary software.

You made a positive claim that that software qualifies as open source. If
we work under the assumption that "open source" has no meaning, then your
claim makes no sense. The absolute most widespread and widely recognized
meaning of "open source" is that which OSI uses, or something very similar,
and is definitely not synonymous with "source available", or broad enough
to include that piece of software.

Since we are talking about a piece of software, specifically, the meaning
of "open source" in other sectors is entirely irrelevant.

> In GNU project we do not use "Open Source" or "Open" when referring to
> "Free Software":

I never suggested that you use the term "Open Source" to refer to free
software, just that you also do not use it to refer to proprietary software.

Doing so isn't illegal, it's just incorrect.