Sometimes, I write latex templates (e.g. to account for department-specific guidelines for theses etc.), and wonder how to license them.
The IEEEtran latex class is licensed under the LaTeX Project Public License (LPPL) v1.3. According to the Free Software Foundation (FSF), this is a free license (which is good), but not compatible with the GNU Public License (GPL) (which may be bad, depending on circumstances). There are also templates for specific IEEE conferences or journals, which to my understanding are licensed in the same way.
What I found
There seems to be some debate about what a latex template is (as distinction from classes or packages). However in this case, I think it is quite straightforward: There is the class (IEEEtran.cls) and there are some templates (e.g. bare_conf.tex), that follow the appropriate layout guidelines. This is what I mean by "template".
If I want to copyleft the content of my work, I can use a Creative Commons (CC) license, which is compatible with the GPL. However, I don't know if a template counts as content (my guess is that it doesn't).
According to this answer, I'm free to license my tex files in any way I like, as opposed to being restricted to the LPPL. So I could just use the GPL, but the FSF recommends to "license your templates under simple permissive terms" (seen here).
I could use two licences (e.g. GNU and LPPL), so the user could decide which one to further use. But this just leaves the user with my original problem.
Is there a GPL compatible license suitable for latex templates, that can be used instead of LPPL?
I have a strong preference for copyleft licenses. The reason why I asked about an alternative to LPPL, which is not copyleft, is that it seems to be a standard license for latex projects.