% Considering Key Sections of the GPL

% Bradley M. Kuhn & Karen M. Sandler

% Tuesday 9 May 2017

# Conditional Permissions

+ A copyleft license grants copyright permissions, conditionally.

+ Think of the phrase: “provided that”

+ “provided that”: appears (in some form) only

+ 4 times in GPLv2

+ 9 times in GPLv3.

# Considering Sections of the GPL

+ GPL hinges on modification and distribution.

# Why Permission to Modify?

+ Your new copyrights are your copyrights:

     + you are fixed it in a tangible medium.

+ Exclusive right of copyright holders:

     + Control on “preparation of derivative works”

     + Distribution of the work.

     + Note the combination of these.

+ Again, see 17 USC§106

+ N.B.: “derivative works” is USA-centric, modify is more international)

# Modification As a Center Provision

+ GPL's central tenant:

+ You can make a modified version of various types privately as much as you'd like.

+ When you distribute that modified version, you have requirements to meet.

+ Technological considerations dictate necessity of more complex rules for

certain types of modifications.

# GPLv2 § 2(a-b)

<span class="fitonslide">

<p>[GPLv2&sect;]2. You may modify your copy or copies of the Program or any

portion of it, thus forming a work based on the Program, and copy and

distribute such modifications or work under the terms of Section 1 above,

provided that you also meet all of these conditions:

<br/>

<br/>

a) You must cause the modified files to carry prominent notices stating

that you changed the files and the date of any change.

<br/>

<br/>

b) You must cause any work that you distribute or publish, that in

whole or in part contains or is derived from the Program or any

  "The Program" refers to any copyrightable work licensed under this

License.  Each licensee is addressed as "you".  "Licensees" and

"recipients" may be individuals or organizations.

<br/>

<br/>

To "modify" a work means to copy from or adapt all or part of the work

in a fashion requiring copyright permission, other than the making of an

exact copy.  The resulting work is called a "modified version" of the

earlier work or a work "based on" the earlier work.

<br/>

<br/>

  A "covered work" means either the unmodified Program or a work based

on the Program.

</p>

# Binaries (Object Code) are Modifications

+ Software that the computer understands is different than software humans

  read.

+ There is often a process required to modify (and/or translate) the software

  from human-readable

      + This process can be done ahead of time.

      + GPL uses the fact that binaries are modifications (which are often

# GPLv2 § 3(a-b)

<span class="fitonslide">

<p>

<p>[GPLv2&sect;]3. You may copy and distribute the Program (or a work based on it,

under Section 2) in object code or executable form under the terms of

Sections 1 and 2 above provided that you also do one of the following:

<br/>

<br/>

a) Accompany it with the complete corresponding machine-readable

source code, which must be distributed under the terms of Sections

1 and 2 above on a medium customarily used for software interchange; or,

<br/>

<br/>

b) Accompany it with a written offer, valid for at least three

years, to give any third party, for a charge no more than your

cost of physically performing source distribution, a complete

machine-readable copy of the corresponding source code, to be

distributed under the terms of Sections 1 and 2 above on a medium

customarily used for software interchange;

</p>

</span>