1                    NETHACK GENERAL PUBLIC LICENSE
2                    (Copyright 1989 M. Stephenson)
3
4               (Based on the BISON general public license,
5                   copyright 1988 Richard M. Stallman)
6
7 Everyone is permitted to copy and distribute verbatim copies of this
8 license, but changing it is not allowed.  You can also use this wording to
9 make the terms for other programs.
10
11  The license agreements of most software companies keep you at the mercy of
12those companies.  By contrast, our general public license is intended to give
13everyone the right to share NetHack.  To make sure that you get the rights we
14want you to have, we need to make restrictions that forbid anyone to deny you
15these rights or to ask you to surrender the rights.  Hence this license
16agreement.
17
18  Specifically, we want to make sure that you have the right to give away
19copies of NetHack, that you receive source code or else can get it if you
20want it, that you can change NetHack or use pieces of it in new free
21programs, and that you know you can do these things.
22
23  To make sure that everyone has such rights, we have to forbid you to
24deprive anyone else of these rights.  For example, if you distribute copies
25of NetHack, you must give the recipients all the rights that you have.  You
26must make sure that they, too, receive or can get the source code.  And you
27must tell them their rights.
28
29  Also, for our own protection, we must make certain that everyone finds out
30that there is no warranty for NetHack.  If NetHack is modified by someone
31else and passed on, we want its recipients to know that what they have is
32not what we distributed.
33
34  Therefore we (Mike Stephenson and other holders of NetHack copyrights) make
35the following terms which say what you must do to be allowed to distribute or
36change NetHack.
37
38
39                        COPYING POLICIES
40
41  1. You may copy and distribute verbatim copies of NetHack source code as
42you receive it, in any medium, provided that you keep intact the notices on
43all files that refer to copyrights, to this License Agreement, and to the
44absence of any warranty; and give any other recipients of the NetHack
45program a copy of this License Agreement along with the program.
46
47  2. You may modify your copy or copies of NetHack or any portion of it, and
48copy and distribute such modifications under the terms of Paragraph 1 above
49(including distributing this License Agreement), provided that you also do the
50following:
51
52    a) cause the modified files to carry prominent notices stating that you
53    changed the files and the date of any change; and
54
55    b) cause the whole of any work that you distribute or publish, that in
56    whole or in part contains or is a derivative of NetHack or any part
57    thereof, to be licensed at no charge to all third parties on terms
58    identical to those contained in this License Agreement (except that you
59    may choose to grant more extensive warranty protection to some or all
60    third parties, at your option)
61
62    c) You may charge a distribution fee for the physical act of
63    transferring a copy, and you may at your option offer warranty protection
64    in exchange for a fee.
65
66  3. You may copy and distribute NetHack (or a portion or derivative of it,
67under Paragraph 2) in object code or executable form under the terms of
68Paragraphs 1 and 2 above provided that you also do one of the following:
69
70    a) accompany it with the complete machine-readable source code, which
71    must be distributed under the terms of Paragraphs 1 and 2 above; or,
72
73    b) accompany it with full information as to how to obtain the complete
74    machine-readable source code from an appropriate archive site.  (This
75    alternative is allowed only for noncommercial distribution.)
76
77For these purposes, complete source code means either the full source
78distribution as originally released over Usenet or updated copies of the
79files in this distribution used to create the object code or executable.
80
81  4. You may not copy, sublicense, distribute or transfer NetHack except as
82expressly provided under this License Agreement.  Any attempt otherwise to
83copy, sublicense, distribute or transfer NetHack is void and your rights to
84use the program under this License agreement shall be automatically
85terminated.  However, parties who have received computer software programs
86from you with this License Agreement will not have their licenses terminated
87so long as such parties remain in full compliance.
88
89
90Stated plainly:  You are permitted to modify NetHack, or otherwise use parts
91of NetHack, provided that you comply with the conditions specified above;
92in particular, your modified NetHack or program containing parts of NetHack
93must remain freely available as provided in this License Agreement.  In
94other words, go ahead and share NetHack, but don't try to stop anyone else
95from sharing it farther.
96