[pdftex] license questions

[ruu at pacbell.net]

Hi,

I am confused about the license for pdfTeX.

At http://www.tug.org/applications/pdftex/README, there is README 
text that starts out saying 'pdfTeX is free software' but then the text says 
it's covered by the GNU public license.  That's fine.  But then it says 
parts are covered by a copyrights held by Donald Knuth and Peter 
Breitenlohner.  It then says to see the source files for details.
The GNU Public License seems to be the only document I need to rely 
on, as the GNU Public License text is emphatic that by incorporating 
other code, that code then becomes covered by the GNU Public 
License for the purposes of that incorporation.
In addition, the README text only says that parts of pdfTeX are 
covered by 'copyrights' owned by Knuth and Breitenlohner, not 
'licenses,' which again makes me think I only need to rely on the GNU 
Public License.
However, I would like to examine the source files for clarification, as the 
README suggests.  However, I don't know how to.  I am running 
Windows 2000, and I can't seem to do anything useful with the 
source.tar.bz2 file I downloaded from ftp://www.tug.org/texlive/Source/.  
I tried using WinZip on it, but it just created another archive file, and 
didn't show me what files, if any, are inside source.tar.bz2.  Is 
source.tar.bz2 meant to be 'opened,' or is it some kind of a Unix cdrom 
image or something similar?
My main interest is whether there are any restrictions on running 
pdfTeX or pdfLaTeX in a commercial context.  I want to be very sure of 
the answer, which is why I am probing into this issue so much.  I am 
pretty sure I can run pdfTeX and pdfLaTeX without restriction, but I 
can't find anything that explicitly says so.
Thanks.