Hi Ian and colleagues,
That raises important issues which I had not fully understood. GPL v2 and LGPL are similar. The text of the GPL v3 is substantially different from either GLP v2 or LGPL. The difference is that GPL v2 and LGPL are about the responsibilities of the person distributing the work, while GPL v3 is much more concerned to define the rights and responsibilities of the person receiving and using the work (and potentially modifying it for their own and others use).
I am not sure the GPL v3 is actually quite as restrictive as Ian says. Under "Source code" section 1, there is a discussion of "System Libraries" which are outside the scope. Also the concept of the "Corresponding Source" says "However, it does not include the work's System Libraries or general purpose tools or generally available free programs which are used unmodified in performing these activities but are not part of the work".
For question 1, the problem of conflicting licenses will only arise when we want to incorporate with modifications the source code of a routine which has some other form of licensing.
Therefore, there is no detriment in using, say, the VB.NET libraries and tools, or even of incorporating unmodified packages to do certain jobs, provided the attribution of those packages is preserved.The specific example would be to use some of the Scitools library functions (which are under LGPL). Provided these are used but not modified within Climsoft, there is no conflict.
For question 2, the key passage is in section 7, where it says "If the program as you received it, or any part of it, contains a notice stating that it is governed by this license along with a term which is a further restriction, you may remove that term." Hence distributing a package which contains the whole of Climsoft plus some add-ons would imply that the add-ons inherit the GPL v3 rather than any other conditions. However, distribution of add-ons separately from the Climsoft core does not carry any such implications. In favour of using GPL v3 is section 10 - Automatic Licensing of Downstream Recipient, which very clearly prevents anyone from imposing further restrictions - LGPL is much weaker.
The danger for Climsoft is that some other developer changes something in the program and then imposes a condition which takes control away from the Project Team - GPL v3 specifically prevents this. I am relaxed about people adding extra functionality outside the core, and this could be done commercially. GPL v3 section 4 allows commercial consultancy services for e.g. installation and training. Commercial consultancy could also include changes to the program - but they would still be under GPL v3, and therefore those changes would be available to everyone.
The discussion at http://www.gnu.org/licenses/why-not-lgpl.html says that the LGPL is appropriate for libraries intended for use by others, including commercial developers. I can see this is the better option for Scitools, but Climsoft is not a library, it is a complete program.
My opinion is that we should use GPL v3 because it will not stop us doing anything we need to, and it stops others from doing things which would damage the use of Climsoft. Final point - GPL v3 is much stronger on the Disclaimer of Waranty and Limitation of Liability in sections 15, 16 and 17 (section 17 is missing from GPL v2).
Opinions and thoughts please.