NOTE: This FAQ is a simplified explanation and not legally binding in
its details. See the license text itself for precise details.


Who owns the MML?

The owner, as far as copyright is concerned, of the MML is the SUM (in
Polish: Stowarzyszenie Uzytkownikow Mizara, in English Association of
Mizar Users - AMU). However, the SUM permits other people to use and
redistribute the MML under some conditions.

Each contributor also gets special permission to do anything he
wishes, without any condition, with his own contribution.


Who can use the MML?

Anybody can use the MML for any purpose whatsoever without any
restriction nor obligation, as long as "use" does not include
redistributing (giving a copy) of (part of) the MML, nor any article
using the MML, to any third party.

"Using" the MML typically entails using definitions / theorems /
schemas / notations / ... from the MML to write new proofs, or to
add, delete or modify definitions / proofs / ... in the MML.


What do I have to do if I want to redistribute the MML, or part
thereof, unmodified?

You have to inform the people you give the MML to of their rights and
obligations. Specifically, include the files COPYING.* in the copy you
redistribute. You may not forbid other people to exercise the rights
given to them by the SUM.


What do I have to do if I want to redistribute (part of) the MML,
modified or augmented, or an article that invokes (a) theorem(s) /
notation(s) / scheme(s) / ... from the MML?

These instructions assume you do not wish to assign copyright of your
work to the SUM.

0) Don't remove or alter the SUM copyright notice.

1) Add to the header of the file:

   Copyright © YEAR_OF_MODIFICATION YOUR NAME <your_email@example.org>

   If your employer owns your work, that would be:

   Copyright © YEAR_OF_MODIFICATION YOUR_EMPLOYER <employer_email@example.org>

2) You have to give others the same rights you got, that is you have
   to license your modifications and your new articles under the GNU
   GPL v3 (or later), the Creative Commons BY-SA v3 (or later), or
   (preferably) both.

   If your employer owns your work, this requires his/her permission.

3) Briefly describe what you changed as a comment in the header or
   footer. E.g.:
   "Changed proof of theorem Cayley_Hamilton to follow proof by Shamir
    and Slotzky in their book 'Introduction to Linear Algebra for
    Dummies - the Collegiate Edition'"
   or
   "Add new redefinition of real numbers as sub-category of surreal
    (Conway) numbers"

4) Include the files COPYING.* in what you redistribute.

The likely (and intended) effect of this is that sooner or later your
modifications will become public, even if you choose to distribute it
to precious few: some of them will redistribute to someone that will
redistribute, ... and someone in the chain will just make it public.


What do I have to do if I want my enhancements to go into the
"official" version of the MML, distributed by mizar.org?

1) Sign the Fiduciary Licensing Agreement, if you have not already
   done so.

   If you live in France, sign the FLA again even if you did so in the
   past. Also for other jurisdictions that do not allow you to assign
   future work.

2) Update the SUM copyright line to include the current year. The
   format is: comma-separated list of disjoint singletons and
   hyphen-separated ranges of years, in increasing order.

   E.g. for modifications you did in 2010, change

   Copyright © 1989-1995 Association of Mizar Users
                         (Stowarzyszenie Uzytkownikow Mizara, Białystok, Poland).

   to

   Copyright © 1989-1995,2010 Association of Mizar Users
                         (Stowarzyszenie Uzytkownikow Mizara, Białystok, Poland).

   Change

   Copyright © 1989-2009 Association of Mizar Users
                         (Stowarzyszenie Uzytkownikow Mizara, Białystok, Poland).

   to

   Copyright © 1989-2010 Association of Mizar Users
                         (Stowarzyszenie Uzytkownikow Mizara, Białystok, Poland).

   For new articles, put in the header:

   Copyright © 2010 Association of Mizar Users
                         (Stowarzyszenie Uzytkownikow Mizara, Białystok, Poland).

3) Send the signed FLA, along with your enhancements to the MML, to
   the Mizar project.


Can I write a program that uses the MML?

Yes, you can. However, if you wish to *distribute* this program,
please observe the following: no restriction is put on your program as
long as it does not contain (part of) the MML itself. Your program can
use the MML as data. E.g. you can write a Mizar implementation, a
proof transformer / converter, ... In this case, no restriction is put
on your program. However, the result of running your program over the
MML (e.g. proofs converted to Isar or HOL Light, beautified proofs,
...) is still covered by the SUM copyright and subject to the same
permissions and conditions as the original MML.

If (part of) the MML ends up in your program itself, even in another
shape than text files (e.g. as a parse tree or memory dump that is in
the executable file), then your whole program needs to be released
under the GNU GPL, or a license compatible with it (e.g. 2-clause BSD,
X11/MIT, ...). See
http://www.gnu.org/licenses/license-list.html#GPLCompatibleLicenses

A good rule of thumb is: If

 - your program compiles and links completely without the build
   process using (part of) the MML (in any shape) at all;

 - the compiled program is byte-to-byte identical to the compilation
   in the presence of the MML;

 - the compiled program is independently useful (for example, it would
   be useful on an article written in the Mizar language that does not
   use the MML);

then there is probably no restriction on your program. Your program
can e.g. use the MML in its automated test-suite: when you run the
test-suite, your program is already fully compiled.

Obviously, if you distribute the MML along with your program, you
still have to obey the conditions for the MML.


I want to do something not allowed by the license.

Get in touch with the SUM, explaining what you want to do, why you
cannot do it under the terms of the GNU GPL or CC-BY-SA, and why the
SUM should allow that.

If your project advances science ands its broad availability to
humankind, you may get permission from the SUM.

If you wish to commercially exploit the MML, the SUM may be willing to
sell you a license that fits your needs. E.g. if you want to integrate
the MML into an interactive exercise system for mathematics system and
you sell (access to) this system.


What is the story with the two licences? Do I have to obey both?

No, you may choose either of them, and obey only that one. Please
indicate your choice clearly. All instructions in this FAQ refer to
the common denominator between the two licenses.


I submitted an enhancement to a MML article, and it got accepted. Can
I do anything (e.g. sell copies of or a commercial license on) the
whole article?
I wrote an article for the MML. Can I do anything with future versions
of the article?

No, the special permission to contributors to do anything they wish
applies only to your own work.

So, in the first example, it applies only to your enhancement, not the
whole article (that includes work by other people). Naturally, if you
cooperate with (or get permission from) all other authors of all
previous versions of this article, you all together as a group may do
anything you wish.

Similarly, if you submit a new article to the MML, the special
permission applies only to your original version (plus any enhancement
you make), not to any version that includes any change by another
contributor.


May I distribute a printed version of (part of) the MML?

Yes, and e.g. a PDF counts as "printed version", but you must:

1) Give people an electronic copy of the MML in source form (preferred
   form for modification) on a medium customary at the time, or a
   URL/URI to a free of charge download link for the MML in source
   format. If you print the unmodified MML, this can be a link to the
   (version of the MML you print) hosted at mizar.org, or any other
   download server, such as your own. If you modified the MML before
   printing, you have to organise your own download service.

2) Mention the SUM copyright, and state that the articles are free to
   use / modify / redistribute under the GPL and/or the CC-BY-SA,
   and include a copy of the GPL and/or CC-BY-SA, or at least the URL
   to the license(s).

3) Effectively allow people to exercise their rights. E.g., you may
   not use DRM techniques or anti-photocopy backgrounds to keep people
   from further distributing / sharing / copying the printed version.

   If you e.g. publish a MML article as part of a journal, this
   restriction does not apply to your whole journal, nor the whole
   issue in which the MML article appears, only the MML article
   itself.

You are not legally obligated to publish the pretty-printing program
you used (if any), but it would be appreciated if you did and licensed
it under a Free / Open Source license.
