vis as a whole is licensed under the following standard ISC license:

 Copyright © 2014-2020 Marc André Tanner, et al.

 Permission to use, copy, modify, and/or distribute this software for any
 purpose with or without fee is hereby granted, provided that the above
 copyright notice and this permission notice appear in all copies.

 THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

Portions of this software are derived from third-party works licensed
under terms compatible with the above ISC license:

 - ./configure is based on the corresponding script from the musl libc
   project and is MIT licensed

 - map.[ch] originate from the Comprehensive C Archive Network strmap
   module and are public domain / CC0 licensed

 - libutf.[ch] originate from libutf a port of Plan 9's Unicode library
   to Unix and are MIT licensed

 - sam.[ch] is heavily inspired (and partially based upon) the X11
   version of Rob Pike's sam text editor originally written for Plan 9
   and distributed under an ISC-like license

 - lua/lexers/* the LPeg based lexers used for syntax highlighting are
   imported from the Scintillua project licensed under the MIT license

Check the individual source files for more specific copyright information.

Details on authorship of individual files can be found in the git version
control history of the project. The omission of copyright and license
comments in each file is in the interest of source tree size.