[OpenFontLibrary] New work on fonts at W3C
chris at w3.org
Tue May 12 07:07:21 PDT 2009
W3C is collecting ideas for work related to downloadable fonts on the Web. This email summarizes the current situation, and asks for feedback on a draft charter  for a future W3C Font working group or interest group. Please send feedback on the charter to the publicly archived mailing list www-style at w3.org.
The method of linking to fonts from CSS stylesheets or from SVG content - WebFonts - is already standardized in CSS2  and SVG 1.1 . That work is being refined in the CSS3 Fonts module , for the CSS serialization. SVG 1.1 allows both CSS and XML serialisations of WebFonts. SVG Tiny 1.2 uses the XML serialisation. XSL may use the WebFont mechanism in future, in the XL serialization.
CSS2 WebFonts allows for font matching, font synthesis, and font download. of those, only font download has been implemented in multiple user agents.
What has hindered deployment, however, has been the choice of what font format to download.
CSS2 suggests several formats, none of them being required for compliance. Microsoft implemented WebFonts in IE4, using the then-proprietary EOT encoding of an OpenType font. EOT (and the related MicroType Express format) have since been documented in a submission to W3C  with the promise of royalty-free commitments, if the EOT and MicroType Express formats form part of a W3C Recommendation.
SVG requires one format (SVG fonts) and allows others to be linked. Adobe implemented WebFonts in ASV, supporting SVG and CFF (a subset of OpenType, using only Type 1 glyphs). Apache implemented WebFonts in Batik, supporting the SVG format. Opera implements WebFonts with SVG, and the fonts may be applied to SVG, HTML, or mixed SVG/XHTML content.
Several Web browsers now implement WebFonts, with the OpenType format: Firefox 3.5 (beta 4 was tested), Safari 3.1 and 4, and Opera 10 (alpha). W3C has produced tests for complex international script rendering with downloadable fonts; the test and results are available . (Firefox 3.5 beta 4 results are yet to be added to this table).
Font licenses vary. Some fonts, libre, are provided with source code and permit extension, modification, and redistribution. The Open Font Library  collects such libre fonts. Other fonts may be downloaded and used, but may not be changed, subsetted, or converted to another format. (Often such fonts are contained in zip files; being able to link to a specific font inside a zipfile is desirable).
Some fonts are licensed to a specific site or domain. EOT provides one way to indicate this in the font itself. Cross Origin Resource Sharing (CORS, previously known as Access Control) is a W3C specification which may also be used to indicate this . Mozilla Firefox restricts downloadable OpenType fonts to those permitted by CORS.
There may be other ways to indicate metadata, so that foundries and font licensees may indicate the nature of their agreement.
Lastly there are of course fonts intended for use exclusively with print, whose licenses explicitly preclude use on the Web.
Please take a moment to read and comment on the proposed charter  which is a work in progress.
Chris Lilley mailto:chris at w3.org
Technical Director, Interaction Domain
W3C Graphics Activity Lead
Co-Chair, W3C Hypertext CG
More information about the OpenFontLibrary