(This post is part of a series recapping the October 2018 W3C Strategic Highlights and does not include significant updates since that report.
WOFF 1.0 and WOFF 2.0, published as a Recommendation last winter, are widely implemented W3C Recommendations. However, for fonts with many glyphs (such as are typically used for Chinese and Japanese, for example), even with the compression provided by WOFF, download sizes are still large. Static subsetting runs the risk of missing glyphs, or some text being rendered in a fallback font.
Early experiments have demonstrated the feasibility of a font enrichment API, where a server delivers a font with minimal glyph repertoire and the client can query the full repertoire and request additional subsets on-the-fly. The API takes care of progressively enriching the downloaded font, without requiring cumbersome CSS manipulations or multiple, separate font files. This API could be implemented as a script library, or as a native browser API. In other experiments, the Brotli compression used in WOFF 2 was extended to support shared dictionaries and patch update. This avoids the need for a new API or a new transport protocol. It still requires the browser to implement dynamic patching and refresh of in-use font resources.
The Fonts Working Group was recently chartered to examine, and solve, this font enrichment issue.