So, the interesting part is §2, which is why it is listed last. And as a short summary: We think that aspects of this section make the license unsuitable for works in Debian main. Taking §2b first. This subsection is in itself ok, DFSG 4 does allow to require a different name for a distribution of modified version, although "similar names" seems to be a bit of a gray area. The major issues arise in subsections §2a and c. These two subsections include between them an invariant section. This type of invariance is not something covered by DFSG 4. DFSG 4 tries to allow a copyright holder to say "If you change foo, you must not call it foo", but does not have similar provisions to allow a copyright holder to say things such as "You must not call foo by any other name" or "If you change foo, the name you must use is bar". Especially noting the parenthetical statement at the end of DFSG 4, we don't believe it would be in the spirit or intent of the DFSG to make the leap that would be required to say that §2a and c are allowed by this clause. The vote taken by the Debian project relating to the GFDL also reinforces the project's dislike for invariance in main. It is also unclear as to whether "font name" refers to the name of the font file on disk, the package name, some form of internal font name or a combination of these. If the reference is to the name of the font file or the internal font name, this becomes a restriction on how you can modify the software, which also fails to comply with DFSG 3. Additionally §2c states exactly how you must change the name to follow the license, which will cause issues if you want to combine multiple fonts licensed using this license into a new derivative work, possibly even making this impossible. This on its own is not a reject reason.