[This question is an expansion of the question "Meaning of OFL and GPL" because of limits on the number of characters in comment-responses].
I am unsure of the meaning of the terms "and" and "additionally" in a license when they connect two named OpenSource licenses (GPL v2 +FE and SIL OFL 1.1, in this case). This pertains to the Libertine Open Fonts Project, whose license appears to have a number of issues.
Does "and" mean that both licenses must apply? I have heard that GPL and SIL OFL are incompatible, and that opinion seems valid (to me) because the reserved name clause of OFL would constitute an additional restriction, disallowed by GPL.
Could "and" mean "either GPL or OFL, at my choice"? I suspect that this is the intent of the authors of the license declaration, but taking "and" to mean "or" is quite a stretch.
As it stands, neither I nor anyone else can make use of the font as appears to be intended.
I am working with the JAIST version of Libertine (ftp.jaist.ac.jp/pub/CTAN/fonts/libertine) as well as the SourceForge version (sourceforge.net/projects/linuxlibertine/). Both appear to be version 5.3.0, and both have font files stamped with version 5.300 and a creation date of July 1, 2012, but the two packages have different contents.
The JAIST variant has a README file at the root level indicating "version 5.3.0 (2018-01-03)" which states:
The original opentype fonts were created by Philipp H. Poll (gillian at linuxlibertine.org) and are licensed under the terms of the GNU General Public License (Version 2, with font exception) and under the terms of the Open Font License.
The JAIST variant's /doc/LICENSE.txt file states (in part):
Our fonts are free in the sense of the GPL. ... Further information about the GPL (licence text with font exception see GPL.txt in this package). Additionally our fonts are licensed under the Open Fonts License (see OFL.txt).
The JAIST variant's /doc directory contains a GPL.txt file for v2+FE, but no OFL.txt file.
The SourceForge variant has a /ttf/README.txt file that states:
"We publish our fonts under the terms of the GPL (see GPL.txt) and OFL (OFL.txt) -> see also LICENCE.txt!"
The SourceForge variant has a /ttf/LICENSE.txt file that matches the JAIST /doc/LICENSE.txt file:
"Additionally our fonts are licensed under the Open Fonts License (see OFL.txt)."
The SourceForge variant's /ttf directory contains a GPL.txt file for v2+FE, and an OFL-1.1.txt file for SIL OFL 1.1..
I am wondering what my position is regarding using these fonts under SIL OFL 1.1. In particular
What does the connector "and" mean between two licenses? (As used in the JAIST variant's README file and also the different text in the SourceForge variant's README.txt.)
What does the conjunctive adverb "Additionally"" mean in the LICENSE.txt file of both variants? ("Additionally our fonts are licensed under the Open Fonts License ..."_.)
What happens when a licence references a file that is missing from the distribution? (As in the JAIST version's OFL.txt file)
What happens when a license referenes the wrong file name? (The SourceForge variant references OFL.txt, but the file is OFL-1.1.txt.)
What if a license statement has the terms in two languages? Which is binding? (German and English are included in the LICENSE.txt file of both variants.)
Sorry for so many questions ... I'm really just trying to clear this font for further development under SIL OFL 1.1. These all seem to be stumbling blocks, but mostly the first or second issue ...