Subject: Re: GPL clause 2a: How do YOU document your changes?
From: Taran Rampersad <cnd@knowprose.com>
Date: Mon, 05 Jan 2004 15:08:16 -0500

Ian Lance Taylor wrote:

>"La Monte H.P. Yarroll" <piggy@timesys.com> writes:
>
>  
>
>>Clause 2a of the GPL states:
>>
>> >   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:
>> >
>> >     a) You must cause the modified files to carry prominent notices
>> >     stating that you changed the files and the date of any change.
>>
>>This clause differs from the practices I have observed in the community.
>>
>>In particular, it is common to simply include a notice that the program
>>as a whole has been changed (e.g. in a README) from some "original"
>>distribution, rather than putting that notice on each modified file.
>>
>>I've also noticed that it is unusual to find a list of specific changes
>>with dates on them.
>>
>>I'm not too concerned about fixing the practices of every project we
>>contribute to.  Mainline changes are generally managed by the primary
>>copyright holder who certainly has a special status wrt to the GPL.
>>
>>I'm more concerned about specialized forks of GPL'd projects which my
>>company maintains.  A lot of project maintainers are not particularly
>>concerned with incorporating changes to support embedded real-time
>>applications.
>>
>>Do you maintain a fork of a GPL'd program?  If so, what do you do to
>>comply with this clause?
>>
>>What do you recommend that we do?  Is an automtically-generated
>>changelog in each file sufficient?  Is it overkill?
>>    
>>
>
>The clause is ambiguous.  It doesn't say that each individual modified
>file must carry a ``prominent notice.''  Instead it says that ``the
>modified files'' must carry ``prominent notices.''
>
>I believe that most people working with GNU sources satisfy this
>clause by distributing a ChangeLog file which describes each change,
>including the specific files and the date.  This is either added to
>the usual ChangeLog file, or a more specific ChangeLog.company file is
>created.  I think that qualifies as a ``prominent notice.''  There is
>no notice on each specific modified file, but the notice is part of
>``the modified files.''
>
>That is what my past and present employers have done to satisfy this
>clause.  I've never heard a complaint that this is inadequate.  I
>think it clearly satisfies the spirit of the clause, and it arguably
>satisfies the letter of the clause as well.
>
>Ian
>  
>
All I could add to this, perhaps, are comments in the source files 
pointing to the relevant ChangeLog file. It's an easy thing to do.

Taran