Embedded OpenType

Embedded OpenType

Filename extension	.eot
Internet media type	application/vnd.ms-fontobject
Type of format	outline font

Embedded OpenType (EOT) fonts are a compact form of OpenType fonts designed by Microsoft for use as embedded fonts on web pages. These files usually use the extension ".eot".

These font files can be created from existing TrueType font files using Microsoft's Web Embedding Fonts Tool (WEFT). (A similar software product called "FAIRY", by BorWare AG, also generated .eot files, with some improvements. [1])

The font files are made small in size by use of subsetting (only including the needed characters), and by data compression (LZ compression, part of Agfa's MicroType Express).

Simply including fonts in webpages might lead to unrestricted copying of copyrighted font files. Like most font embedding schemes, Embedded OpenType includes features to discourage copying. Subsetting reduces the value of copying, as subsetted fonts will typically omit more than half of the characters. Tethering is also employed, using encryption and a list of "trusted roots" at the source end, and a proprietary decrypting DLL at the receiving end.

If the embedded font is not available to the web page for any reason (missing font file, wrong keys in the file, non-support by the web browser), then the second-choice font specification is used, ensuring that the page should be readable even without the intended font.

Embedded OpenType is a proprietary standard supported exclusively by Internet Explorer.

See also

• OpenType
• TrueType
• Portable Font Resource

External links

• Microsoft Typography - Font Embedding for the Web
• Microsoft Typography - Web Fonts Embedding Tool
• MSDN: About font embedding
• CSS2: Fonts