My understanding is that mixing the Artistic License and LGPL 2.1 is not possible. I base this primarily on the FSF statement that they consider the Artistic License to be incompatible with the GPL. I have not found a statement about compatibility between the Artistic License the LGPL.GPL is definitely != LGPL in this area, but I'd appreciate other comments on the issueI tried to read and understand the Artistic License but I got confused. The simplest conflict seems to be that the Artistic License says "You may not charge a fee for this Package itself." where ""Package" refers to the collection of files distributed by the Copyright Holder, and derivatives of that collection of files created through textual modification." This is in conflict with the LGPL 2.1 clause "You may charge a fee for the physical act of transferring a copy".This may well be a problem for combining things into a single package, but I would not have thought it was an issue for things in different packages.I have talked with one of the authors of JUMBO/CML and they may be willing to relicense under the Artistic License 2.0. In doing the research for that I read that the FSF considers the 2.0 license compatible with the GPL because of the relicensing clause 4(c)(ii), which allows the GPL.In this case the whole work would be distributed under the full GPL, not the LGPL
I may (well) be wrong, but I've always understood the INTENT of the artistic licence to be "BSD plus a trademark licence".
But, if the JUMBO/CML people are happy, why not ask them to add an extra permission, or dual-licence. If they are the copyright holders (and therefore able to change the licence from Artistic to Artistic 2), they could always change the licence to "Artistic 1 or LGPL2.1" if they wanted.
If, however, they do change to Artistic 2 (probably a good idea, the original Artistic licence has been slated as being very poor legalese) ...
If it is possible to relicense and be compatible with the LGPL 2.1, the main CDK developer wants to know how to relicense the software. Does he need to make a specific source release of JUMBO/CML under the LGPL 2.1 then turn around and use it inside of his code? Or can CDK include the JUMBO/CML code and just state somewhere inside the CDK documentation "Originally under the Artistic License 2.0 and relicensed under clause 4(c)(ii) to the LGPL 2.1"?
I'm always wary of explicitly relicencing. The GPL doesn't permit it, and by doing so you are taking away user rights.
If you're distributing JUMBO/CML code *unchanged*, what I'd do is to keep it separate inside the package (in its own directory or something), and in the CDK documentation state that you are distributing JUMBO/CML under the LGPL as permitted by 4(c)(ii) of the Artistic licence.
That way, you're leaving (the licence of) JUMBO/CML unchanged, but distributing CDK (including JUMBO/CML) under the LGPL. And the recipient of CDK can strip JUMBO/CML out of it and use it under the Artistic licence as the author intended.
Cheers, Wol -- Anthony W. Youngman - anthony@thewolery.demon.co.uk