Hendrik Weimer's Quantenblog

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Liberation Fonts Increase Document Interoperability


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Ever wondered why a Word document you received looks garbled when opening it in OpenOffice.org under GNU/Linux? Most likely, this is not a bug in OOo's conversion algorithms, but a problem of missing fonts. Most Word documents use fonts like "Arial" or "Times New Roman", which are copyrighted by Microsoft. While Microsoft used to distribute these so-called "core fonts" for non-Windows users, they no longer do so. There are still places where you can get them legally, but of course this is not a free-as-in-speech solution. Therefore, these fonts are not available by default in many GNU/Linux distros.

While the individual glyphs of a font can be copyrighted, their metrics (i.e., their spatial dimensions) cannot be, and therefore one can create a free set of fonts that look different than their proprietary counterparts, but otherwise behave the same when it comes to things like linebreaking, hyphenation, etc. Red Hat has done just that, and some time ago released the Liberation fonts.

However, due to licensing issues not all major GNU/Linux distros included the Liberation fonts. But after a long wait and the persistent work by several people these issues have finally been settled and the Liberation fonts have been accepted into the Debian archive. Other distros are expected to follow suit soon.

When Red Hat released the Liberation fonts, they were distributed under a license that was GPLv2 + two exceptions. The first exception posed no problem: it simply states that embedding the fonts into a document does not make the document a derivative work, a practice even the FSF recommends for fonts. The second exception, however, proved to be tricky. It contains an anti-Tivoization clause requiring any physical distribution to allow the installation of modified versions.

Now, while such a clause clearly does not make the fonts non-free, it is a potential source of conflict with the GPLv2, as it forbids imposing "any further restrictions" on the recipient. Even the copyright holder is not exempt from this, as he could create an invalid license, which means you cannot distribute the work at all. When the Liberation fonts were initially proposed to be included into Debian, they were rejected for this very reason, especially since Richard Stallman objected such a license in a similar situation.

Fortunately, this is not the end of the story. Red Hat's Tom "spot" Callaway spoke to the FSF and they indicated the license was fine according to them. When I came across this issue, I asked the FSF once more, explicitly pointing them to RMS's point of view. They replied that they definitely consider this license to be valid. And thanks to the persistent work of Holger Levsen, we finally managed to convince the Debian ftp-masters as well.

So let me use this opportunity to thank Tom, Holger and everyone else involved in finally settling this issue.

Copyright 2006--2011 Hendrik Weimer. This document is available under the terms of the GNU Free Documentation License. See the licensing terms for further details.