Question regarding GPL

[Volker Dormeyer]

On Thu, Feb 26, 2004 at 01:09:42PM +0100,
Alfred M. Szmidt <ams at kemisten.nu> wrote:
 >     >     > I have improved a code that is public domain (it has no
 >     >     > copyright). Is it possible to make my improved version
 >     >     > GPL. Is it useful.
 >     > 
 >     >    It is possible
 >     > 
 >     > Only if one considers a work that lacks a copyright header
 >     > something that is in the public domain, which I belive is not
 >     > the case.
 > 
 >    He claimed that it is public domain.
 > 
 > He claimed that it was PD based on the lack of a copyright header,
 > Alex Hudson noted that just because it lacks a copyright header doesn't
 > mean that it is PD.

if this is the case, the "public domain" category description on

   http://www.gnu.org/philosophy/categories.html#PublicDomainSoftware

might be wrong, because it suggests that code without a copyright is public
domain. 

I'm interest in how someone can be certain, wether code without a copyright
header is public domain or not? Does anybody know this?

Regards
Volker

-- 
 Volker Dormeyer	<volker at ixolution.de>