Look at "Legal Questions about Scientific Linux" FAQ:

https://www.scientificlinux.org/documentation/faq/legal

12/05/2011 16:20 +0200, Miguel Angel Diaz wrote:
> Hi.
> 
> I agree with you that packages have their own licenses. 
> 
> But my question follows in other way. Imagine I want to create
> other .iso based on S.L.iso. I need to read .iso license to know if I am
> doing well.
> 
> Regards.
> 
> 
> 
> 
> El jue, 12-05-2011 a las 14:32 +0200, Frank Lanitz escribió:
> > Am 12.05.2011 13:53, schrieb Miguel Angel Diaz:
> > > For each package there is a license, but it should exist a license for
> > > SL. 
> > > 
> > > For example, in Centos you can find a file (GPU.txt or EULA.txt) in a
> > > mirror  http://centos.arcticnetwork.ca/5.5/os/x86_64/ . These files show
> > > version of GPL license.
> > > 
> > > Did anyone find these files to SL ?
> > 
> > Its just not possible IMHO to bundle the iso with one and only license.
> > I'd suggest to check the license of each package or go deeper into
> > detail, why you need this information at all.
> > 
> > Cheers,
> > Frank