The only copyrights in this package are:

intercal.ms, intercal.tex, and intercal.txt are Copyright Donald
R. Woods and James M. Lyon 1973. 

intercal.el is Copyright Eric S. Raymond 1992, with the license:

;; This mode was written by Eric S. Raymond <esr@snark.thyrsus.com>
;; for the C-INTERCAL distribution, and is copyrighted by him 1992.  Free
;; redistribution encouraged.  Someday, maybe, this will be made part of GNU.

I've emailed Eric S. Raymond for clarification, which he supplied.

From: "Eric S. Raymond" <esr@snark.thyrsus.com>
Message-Id: <199606050259.WAA01136@snark.thyrsus.com>
Subject: Re: intercal 0.12 distribution permission?
To: eichin@kitten.gen.ma.us
Date: Tue, 4 Jun 1996 22:59:23 -0400 (EDT)

> So it's clear that we can redistribute intercal.el, but nothing else
> is quite as clear :-) The code is not in public domain, since it
> doesn't *say* it is, so it defaults to copyright the author. Since
> READ.ME does indicate that you are the author, I'd like to know if you
> intend to give redistribution permission (it certainly appears so) and
> if so, would you be so kind as to do it explicitly?

Sure, you're welcome to redistribute. [other comments elided --eichin]
