avra, you seem to be more experienced with licenses than I am. Is it ok when I replace the license header in the MapViewer source files by this
License: modified LGPL with linking exception (like RTL, FCL and LCL)
see: https://wiki.lazarus.freepascal.org/FPC_modified_LGPL
I am far from experienced, and more limited in trying to recognize what to avoid during development of closed source software then in properly understanding licenses. So, I might be more wrong then correct. Having all that in mind I will try to contribute to this discussion.
I want to replace it by
{ (c) 2014 ti_dic MapViewer component for lazarus
Parts of this component are based on :
Map Viewer Copyright (C) 2011 Maciej Kaczkowski / keit.co
License: modified LGPL with linking exception (like RTL, FCL and LCL)
see: https://wiki.lazarus.freepascal.org/FPC_modified_LGPL
}
I believe this would be more appropriate:
{
LazMapViewer Copyright (C) 2014 ti_dic user at Lazarus forum https://forum.lazarus.freepascal.org
Map Viewer Copyright (C) 2011 Maciej Kaczkowski at https://keit.co
This library is free software; you can redistribute it and/or modify it
under the terms of the FPC modified LGPL Version 2.
This program is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE. See the FPC modified LGPL Version 2
license for more details.
You should have received a copy of the FPC modified LGPL Version 2
license along with this library; if not, you can find it at this link:
https://wiki.lazarus.freepascal.org/FPC_modified_LGPL
}
FPC modified LGPL is based on LGPL, so it should be fine to use LGPL code header template with just minor modification of replacing "LGPL" with "FPC modified LGPL Version 2", and URL address instead of Free Software Foundation US postal address. I believe that all text in LGPL code header template is there for a reason, so we should keep it as it is.
Maybe also add a line referring to copying and copying.fpc "in the lazarus distribution" or so.
Looking at \fpcsrc\rtl\COPYING.FPC all I can see is that it states what libs are covered by it, explains linking exception difference from pure LGPL, and allows anyone to "delete this exception statement from your version". So, I think we are safe to not mention link to that file. Besides, everything needed is already in the given URL.
Looking at \fpcsrc\rtl\COPYING.txt I see it's pure LGPL 2.1 license, so I think we should have such file but with the content from our license at
https://wiki.lazarus.freepascal.org/FPC_modified_LGPL#FPC_modified_LGPL_Version_2.
LGPL recommends to "add information on how to contact you by electronic and paper mail", so if ti_dic has some better way of contacting instead of mentioning that he is a Lazarus forum user, he should step forward.
Is ti_dic the only one who should hold copyright of LazMapViewer? Original author is mentioned to hold copyright, but I do not know if other contributors besides ti_dic should be mentioned as well. I am also not sure if they should be mentioned at all.
At the end of LGPL there is a recommendation on "How to Apply These Terms to Your New Libraries" which says:
You should also get your employer (if you work as a programmer) or your
school, if any, to sign a "copyright disclaimer" for the library, if
necessary. Here is a sample; alter the names:
Yoyodyne, Inc., hereby disclaims all copyright interest in the
library `Frob' (a library for tweaking knobs) written by James Random Hacker.
<signature of Ty Coon>, 1 April 1990
Ty Coon, President of Vice
Although this is a recommendation for new libraries, it is not clear to me if "copyright disclaimer" protects original author of the library only in a way that no contributor can claim right to original copyright, or also in a way that no additional copyright can be added to library (even forked one). It is not clear to me if additional copyright holders can be stated besides the original author.
Hopefully someone else will bring more light and correct me where I am wrong.