February 28, 2006

A survey of free font licenses

Author: Bruce Byfield

Suddenly, it's free font license time. The Bitstream Vera license, the starting point for most free font licenses, is several years old. In late January, SIL International's Non-Roman Script Initiative announced the SIL Open Font license. A new draft of the STIX License is due in March, with fonts scheduled to be released in beta in April and in final form in June. Each of these licenses has been developed in consultation with the free and open source software (FOSS) communities and strives to balance the philosophy of the communities with the concerns of font designers.

Why are free font licenses needed? The rights they give users to copy and modify works are similar to those in licenses for free software. Since the GNU Public license has provisions for fonts, and Creative Commons licenses are used for a variety of different media, licenses specifically for fonts might seem to do nothing except add to the growing number of free and open source licenses.

The answer, all the framers of the licenses agree, lies in the concerns of the design community, rather than the nature of the free and open source communities. Like many programmers, font designers see themselves as artists, or at least skilled artisans. Unlike programmers, however, they have centuries of tradition and the acceptance of the greater art community to support their belief.

For this reason, protection of artistic integrity is a main concern in all three licenses. While the licenses allow derivative works, each insists that derivatives must be renamed. The Bitstream Vera license, for example, specifically prevents derivatives from using the words "Bitstream" or "Vera." "It is not enough for a designer to have the ability to disclaim any derivative that they don't like," says Victor Gaultney, one of the writers of the SIL Open Font license. "Designers need the assurance that nothing will outwardly bear their name (or the name of their unique font) unless they want it to."

Bob Thomas, director of product management at Bitstream, agrees. Without such a clause, he says, "There might be all sorts of fonts out there with the same name, and they might not be compatible and they might not be very good."

Similarly, the licenses attempt to address the widespread concern in the design communities about having fonts bundled or sold separately on amateur sites or alongside low-quality fonts. "It's amazing to me," Thomas says, "How many people have bought our font collection and then put it online to either resell it themselves or give it away for free."

The solution in each of the licenses is a clause that prohibits the font being sold separately. Instead, it can only be included with a program. To developers, this stipulation may seem absurdly easy to circumvent. Bundling a "Hello, World" script with the font would be enough to meet the condition -- or, as Branden Robinson, the Debian Project Leader, jokes, in some cases, a text file with a haiku. David Turner, GPL Compliance Engineer at the FSF, even goes so far as to say that the ease with which this condition can be met was reason enough for his organization to ignore its misgivings about such a condition in the SIL Open Font license.

Yet the writers of the free font licenses remain unanimous that such a condition is needed, no matter how lax. "Very few (if any) professional font designers would ever consider releasing their work under a FLOSS license if they thought it could be renamed and sold on its own," Gaultney says. Without them, fonts with a free license would probably not exist at all.

The Bitstream Vera License

The Bitstream Vera license originated in discussions between Bitstream and Jim Gettys of the GNOME Foundation. Bitstream, which bills itself as the first digital font foundry, has a history of contributions to GNU/Linux. In 1989, it released the code for its Speedo font rasterizer, an early font rendering engine. It has also developed the btX2 font subsystem for Unix and GNU/Linux, which was licensed by Lycoris (since absorbed by Mandriva), and discussed the possibility of bundling fonts with at least a couple of commercial distributions.

Looking back at Linux at the turn of the millennium, Bitstream's Bob Thomas says, "The fonts that were out there were not very good. People had been complaining about [them], so we thought that it would help benefit the community and perhaps give us more exposure within the community."

Bitstream decided to release the Vera typeface, which was developed in-house by Jim Lyle, Bitstream's director of typographical development. Although some type aficionados have criticized Vera as having ugly macrons and other diacritical marks, in most ways Vera was an ideal choice. With regular strokes and wide letter forms, the font family is well-hinted and scores high on readability and legibility, making it ideal for online viewing. The monospaced version of Vera has proved especially popular among programmers, according to Thomas.

Bitstream released 10 Vera fonts: Roman, Oblique, Bold, and Oblique Bold weights for Vera Sans and Vera Mono, and Roman and Bold for Vera Serif.

The fonts and their license were released on April 16, 2003. The license was unusually simple, consisting of less than three dozen lines -- about half of it a standard disclaimer of no warranty or liability -- and containing language to forbid the selling of the font by itself or releasing modifications under the same name. First used by GNOME, the fonts and their licenses were quickly accepted by the Open Source Initiative. The debian-legal mailing list debated the new license at length, and, according to Thomas, Richard Stallman initially questioned the need for a license specifically for fonts, but the final form of the license was accepted in the FOSS communities with few difficulties. Now, the font is ubiquitous in GNU/Linux distributions.

Thomas gives Jim Gettys much of the credit for the license's acceptance. In Bitstream's dealing with the communities, Thomas says, "Jim Gettys was essentially our point person. He was very helpful in that respect."

Bitstream is about to release new versions of the Vera fonts with Thai and Central European characters. Thomas says that Eastern European, Greek, and Turkish characters may follow, although possibly only in one weight. Any new versions will be released under the same license, but Bitstream has no current plans for using the license to donate other fonts.

Today, the Bitstream Vera license is used by a number of other free fonts, including the Vera derivative Bera. It remains the starting point for thinking about free font licenses.

The STIX License

The STIX project is preparing a comprehensive set of Unicode fonts for scientific and engineering purposes. It is supported by a broad array of scientific associations and publishers, including the Institute of Electrical and Electronics Engineering, the American Institute of Physics, the American Chemical Society, the American Mathematical Society and the American Physical Society. Although developers are solicited on the site, since 2000 most of the work on the fonts has been contracted to MicroPress, a company that specializes in TeX technologies.

This long timeline is explained by the need to have STIX proposals approved as part of the Unicode formatting tables, as well as the sheer number of glyphs (characters) needed -- 8,064, to be exact. Initial work on the fonts was due for completion at the end of February. While the fonts are not available to non-STIX members yet, according to the Web site, most glyphs are designed for use with the Times typeface, although sans serif, monospace, Fraktur (German Black Letter), script, and calligraphic versions of some glyphs will also be available.

Paul Dlug of the American Physical Society is advising the STIX project on licensing issues. In looking for an appropriate license, Dlug considered both software and font licenses, include the GNU General Public License, the BSD License, and the Bitstream Vera license. At an early stage, the license was posted on the STIX site, and it is now being revised. Asked if this consultation process affected the license, Dlug says that it "definitely" did.

One unique aspect of the STIX license is that its limits on modification of the fonts specifically excludes conversion of the fonts from one file format to another -- for example, from TrueType to Postscript. Such conversions are commonplace because of users' preferences for one file format. Moreover, as the license specifically recognizes, such conversions are not perfect because of technical differences in formats, and frequently result in unintended alterations.

The published draft of the STIX license was affected by two major considerations. To start with, about one-third of the glyphs in the STIX fonts already existed -- most, if not all of them, owned by MicroPress. Because of this constraint, the draft license allows the addition of glyphs, but no editing of existing ones. In addition, because many of the organizations and companies involved in the project are non-profit, the license forbids mentioning them in advertising.

The trouble is that these restrictions, if they survive into the final draft, will make the license unacceptable in the FOSS communities. Because of the restrictions on modifications, David Turner states, "The license is non-free." Comparing the license with the provisions of the Debian Free Software Guidelines (DFSG), Don Armstrong, a Debian developer who is familiar with licensing issues, agrees. In addition, Armstrong adds, the limits on how derived works are named may be "problematic." A recent discussion on the debian-legal list suggests that many Debian developers would agree.

Tim Ingoldsby of the American Institute of Physics, the leader of the STIX project, states that his intention is for the final version to be a free license. Dlug agrees, suggesting that "it doesn't make sense to make a heavy font license." The challenge, though, will be to reconcile this intent with the restrictions that STIX is under.

SIL Open Font License

SIL International is a Christian organization whose concerns include literacy and the study and preservation of lesser-known languages. A strong proponent of collaborative methods, SIL has advocated them in UNESCO's Project B@bel, a project to assist in the preservation of endangered languages. As part of its efforts, SIL supports the ongoing development of several Unicode-compliant fonts, including Doulos SIL, Charis SIL, and Gentium, which was recently reviewed on NewsForge. In addition to developing fonts, SIL is also involved in developing tools for their use. Two of these tools are Keyboard Mapping For Linux(KMFL), a tool to make complex keyboard mappings easier, and Graphite, a cross-platform library for Unicode text rendering. Another is the SIL Open Font license (OFL).

The OFL was written over the last few years by Nicolas Spalinger, a SIL volunteer whose university research includes collaborative models for non-government organizations, and Victor Gaultney, a typeface designer for SIL. Although Spalinger credits the Bitstream Vera Licence as being a "good inspiration" for their efforts, the OFL is considerably longer and more specific. For example, the license specifically allows the embedding of fonts in formats such as PDF, which usually includes only the glyphs actually used in the document -- a concern mentioned by those involved with all three licenses discussed here, but not specifically covered by the others.

From the start, Spalinger and Gaultney have worked overtime to make the license acceptable to the FOSS community. The main page for the OFL lays out how its creators believe the license is acceptable to both the FSF and Debian. They also consulted the FSF, GNOME, and the Software Freedom Law Center, and asked for opinions on the debian-legal mailing list.

In late January, these efforts were rewarded by the FSF, which listed the OFL as an officially-approved license. In addition, what Spalinger describes as SIL's solution "stack" -- OFL fonts, KMFL, and Graphite -- is scheduled to be included in Ubuntu's Dapper Drake release. Debian, however, is still debating the status of the license. Armstrong believes that the OFL's precise restrictions on the naming of derivatives may be incompatible with the DFSG. Armstrong also suggests that the insistence that all versions of fonts released under the OFL must use the same license makes it incompatible with the GPL. Discussion is ongoing, but, until the issue is resolved, Gaultney's ambition that the OFL become a "generic license that anyone can use" will remain only partly realized.

The growing need for free font licenses

Whether any of these font licenses will survive is uncertain. The earlier Arphic Public License was approved by the FSF, but remains largely unknown. Possibly it was ahead of its time. So far, the Bitstream Vera License seems to have the greatest acceptance, possibly because its brevity allows more interpretation. However, it is still possible that future modifications of the STIX license or the OFL will make them equally acceptable to all parts of the FOSS communities.

Meanwhile, the recent increase of new licences suggests that free operating systems are starting to attract a new class of users with new concerns. As Gaultney says,

Fonts are a rather unique type of artwork/software. A font is not simply a bunch of software routines with an interface, nor is it a photograph or graphic image. It rests between these worlds, and so the models that have been successfully applied to them do not fit well. And so we have seen relatively few high-quality fonts in the FLOSS world.

Whether this situation changes may depend largely on the ability for the communities to evolve acceptable licenses.

Bruce Byfield is a course designer and instructor, and a computer journalist who writes regularly for NewsForge, Linux.com and IT Manager's Journal.

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