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.  Sadly,
I can't find any sources that prove or disprove this; maybe some
copyright law person can comment on this.

Cheerio.