Public domain software is not open-source?

[Rick Moen]

Quoting John Cowan (cowan at ccil.org):

> There is, however, the Olson (zoneinfo) software package, which is widely
> used wherever time zone information is desired.  It, or its derivatives,
> appear in almost every non-Windows operating system, in Java, and in
> many other places.  And because Olson is a U.S. government employee
> (a sysadmin for NIH), the package is ab initio in the public domain.

Thank you for the valuable example.  This would be among the rare
examples of a piece of software that inarguably, non-problematically is 
public domain without legal questions.  Nick also cited another, a
pre-Berne-era package that is believed to have lost title through lack
of notice (though it might be a bit bold to assert that such as package
really did lose copyright title unless a judge ruled that it did).

> Contrariwise, even though truly PD software is not licensed, if it is
> source-available it is perfectly feasible to declare it open-source
> software.  I think the OSI should do so.

One problem is, as you well know, many more pieces of software are
_asserted_ to be public domain than actually are.  For example, when I
was doing an informal licence review of SourceForge.net packages for
PalmOS, for my site's collection of all known free / open source PalmOS
software, I found quite a few allegedly "public domain" packages that,
upon examination, had clear upstream copyright encumbrances that the
project maintainer simply wished to ignore.  (I called the results of my
survey to the SourceForge.net administrators, calling it a problem:
Their reaction was that they simply had no time or resources to enforce
licensing correctness for tens of thousands of projects.)

This problem appears to be particularly widespread on proprietary-OS
platforms:  Assertion of "public domain" most often merely means "I don't
like to even think about licensing and want it to go away -- including
at the expense of third-party rights".  As a potential re-user of code, I
tend to see PD assertions as meaning "Needs a really careful audit."