[sword-devel] LcdBible and licencing

[Eeli Kaikkonen]

On Wednesday 10 December 2003 03:15, Chris Little wrote:

> If LcdBible uses Sword or any other GPLed code, it must be licensed under
> the GPL exclusively.  Code written by Stallman that we have incorporated
> means there's not even the option of permitting another license currently.

If a software library is GPL'ed, you cannot change it's licence. But you can 
write a program which uses that library by dynamically linking with it and 
use any GPL-compatible licence for that program. So you can make a library 
which is a subset of sword library and use GPL licence, then make a program 
which uses that new library and is under LGPL or BSD licence.

You can also incorporate sword code to a program. Then your program must be 
under GPL. But you can dual-licence your own code. It means that in source 
code the parts written by you and written by others are clearly marked (which 
should be done anyways) so that anyone can take your code and use it but 
leave out original sword code. That is of course reasonable if your code has 
some algorithms or something else which can be used independently from sword.

There are two viral effects in GPL. The first is that you must release code 
which has GPL'ed part in it under GPL. The second is that linking dynamically 
with GPL makes the linking program/library to be under GPL, so it's licence 
must be GPL-compatible if you want to distribute the binaries legally.

Understanding licencing issues, especially GPL, is not an easy task. My 
advices are also uncertain even though I have studied this a bit over the 
years.

Eeli Kaikkonen