There are only recommendations, nothing is forced. https://www.gnu.org/licenses/gpl-faq.html#GPLOtherThanSoftware https://www.gnu.org/licenses/gpl-faq.html#GPL

There are only recommendations, nothing is forced. https://www.gnu.org/licenses/gpl-faq.html#GPLOtherThanSoftware https://www.gnu.org/licenses/gpl-faq.html#GPLOtherThanSoftwa... https://en.wikipedia.org/wiki/GNU_General_Public_License#Text_and_other_media https://en.wikipedia.org/wiki/GNU_General_Public_License#Tex...