Question regarding GPL

[Alfred M. Szmidt]

    >     > 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.