[Tcl] and extensions such as [Tk], [Expect], [tcllib] are distributed under the tems of [http://tcl.tk/software/tcltk/license.html%|%this license]. 



** See Also **

   [Licenses]:   more general information about software licenses 



** Description **

The Tcl/Tk license is a [BSD]-type license, which is much less restrictive than
the [GPL].

According to the [https://fedoraproject.org%|%Fedora Project] [http://fedoraproject.org/wiki/Licensing#Software_License_List%|%software license list],  the Tcl/Tk license meets the [FSF] definition of "free software", and is compatible with bot versions 2 and 3 of the [GPL]. 

It is not [http://www.opensource.org%|%OSI] approved, possibly because it has
simply never been considered by the OSI, but the very similar new [BSD] license
is.

The Tcl/Tk license allows binary-only redistribution, which is one key difference compared to the GPL, making it amenable to incorporation into closed-source software. 

The Tcl/Tk license, in contrast to the GPL,  does not require that derived works be released under the the original license: You can start with a piece of code from the Tcl/Tk/tcllib/ sources that does something similar to what you want, modify it to do exactly what you want, use that in a larger project, and still be free to choose the license under which you release this larger project.

----

[Kbk] writes in comp.lang.tcl the following summary of the Tcl license:

======
In even simpler language:

  Paragraph 1. It's ours.
  Paragraph 2. You can use it, modify it, give it away, or sell it. But 
               only if you tell people about these terms.
  Paragraph 3. Don't sue us if it doesn't work.
  Paragraph 4. We don't have to fix it, either.
  Paragraph 5. Even if the Government uses it, we can use it
               ourselves, give it away, or sell it.
======



<<categories>> Tcl | Licence