[dublinben]

Some CC licenses like CC-BY-SA and CC-BY can be compatible with free software licenses. It's often easier to just license the resources of a program the same as the code, so there are no conflicts.

[sadache]

Excuse my ignorance, but can OS licenses be applied to other than code (content, text, images, ... etc) ?

I mean, really ignore the impact of licensing content with OS license, any references?

[dublinben]

Of course. The very last paragraph on this page explains that these licenses can be used for any kind of data.

https://gnu.org/licenses/license-recommendations.html