Embedded OpenType (EOT)

fonts In metal typesetting, a font is a particular size, weight and style of a typeface. Each font is a matched set of type, with a piece (a "sort") for each glyph. A typeface consists of a range of such fonts that shared an overall design. In mode ...

are a compact form of

OpenType OpenType is a format for scalable computer fonts. It was built on its predecessor TrueType, retaining TrueType's basic structure and adding many intricate data structures for prescribing typographic behavior. OpenType is a registered trademark o ...

fonts designed by

Microsoft Microsoft Corporation is an American multinational technology corporation producing computer software, consumer electronics, personal computers, and related services headquartered at the Microsoft Redmond campus located in Redmond, Washing ...

for use as embedded fonts on web pages. These files use the

extension Extension, extend or extended may refer to: Mathematics Logic or set theory * Axiom of extensionality * Extensible cardinal * Extension (model theory) * Extension (predicate logic), the set of tuples of values that satisfy the predicate * E ...

.eot. They are supported only by

Microsoft Internet Explorer Internet Explorer (formerly Microsoft Internet Explorer and Windows Internet Explorer, commonly abbreviated IE or MSIE) is a series of graphical web browsers developed by Microsoft which was used in the Windows line of operating systems (in Wi ...

, as opposed to competing

WOFF The Web Open Font Format (WOFF) is a font format for use in web pages. WOFF files are OpenType or TrueType fonts, with format-specific compression applied and additional XML metadata added. The two primary goals are first to distinguish font file ...

files.

Overview

EOT font files can be created from existing

TrueType TrueType is an outline font standard developed by Apple in the late 1980s as a competitor to Adobe's Type 1 fonts used in PostScript. It has become the most common format for fonts on the classic Mac OS, macOS, and Microsoft Windows operating sy ...

font files using Microsoft's Web Embedding Fonts Tool (WEFT), and other proprietary and open source software (see “External links” below). The font files are made small in size by use of

subsetting In research communities (for example, earth sciences, astronomy, business, and government), subsetting is the process of retrieving just the parts (a subset) of large files which are of interest for a specific purpose. This occurs usually in a clien ...

(only including the needed characters), and by

data compression In information theory, data compression, source coding, or bit-rate reduction is the process of encoding information using fewer bits than the original representation. Any particular compression is either lossy or lossless. Lossless compression ...

(LZ compression, part of Agfa'
MicroType Express
. Like OTF fonts, EOT supports both Postscript and TrueType outlines for the glyphs. Simply including fonts in webpages might lead to unrestricted copying of copyrighted font files. 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. Other copy protection measures used are

encryption In cryptography, encryption is the process of encoding information. This process converts the original representation of the information, known as plaintext, into an alternative form known as ciphertext. Ideally, only authorized parties can decip ...

and a list of "trusted roots" at the source end, and a proprietary decrypting library 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 Internet Explorer (formerly Microsoft Internet Explorer and Windows Internet Explorer, commonly abbreviated IE or MSIE) is a series of graphical user interface, graphical web browsers developed by Microsoft which was used in the Microsoft Wind ...

but wa
submitted to the W3C in 2007 as part of CSS3
which was rejected and resubmitted as
standalone submission March 18, 2008
Th
W3C team comment
on the submission states that the "W3C plans to submit a proposal to the W3C members for a working group whose goal is to try and develop EOT into a W3C Recommendation." However, the W3C ultimately chose a different web font format (

) as a W3C Recommendation. The support for the format has not been built into the

Microsoft Edge Microsoft Edge is a proprietary, cross-platform web browser created by Microsoft. It was first released in 2015 as part of Windows 10 and Xbox One and later ported to other platforms as a fork of Google's Chromium open-source project: Android ...

, the successor to the Internet Explorer.

Web Embedding Fonts Tool

The Web Embedding Fonts Tool, or WEFT, is

's utility for generating embeddable

web fonts Web typography is the use of fonts on the World Wide Web. When HTML was first created, font faces and styles were controlled exclusively by the settings of each web browser. There was no mechanism for individual Web pages to control font display u ...

. WEFT is used by

webmaster A webmaster is a person responsible for maintaining one or more websites. The title may refer to web architects, web developers, site authors, website administrators, website owners, website coordinators, or website publishers. The duties of ...

s to create 'font objects' that are linked to their web pages so that users using Microsoft's

web browser A web browser is application software for accessing websites. When a user requests a web page from a particular website, the browser retrieves its files from a web server and then displays the page on the user's screen. Browsers are used on ...

will see the pages displayed in the font style contained within the font object. WEFT scans the

HTML The HyperText Markup Language or HTML is the standard markup language for documents designed to be displayed in a web browser. It can be assisted by technologies such as Cascading Style Sheets (CSS) and scripting languages such as JavaScri ...

document file(s), the TrueType font file(s), and some additional parameters. It adjusts the HTML files and creates Embedded OpenType files for inclusion on the web site. These files usually use the

'.eot'. WEFT can embed most fonts, but it will not embed fonts that have been designated as 'no embedding' fonts by their designers. WEFT may reject other fonts because problems have been identified. In the past, embedded fonts were widely used to generate non-English-language websites. As of January 2015, the most recent version of the tool (WEFT 3.2) was released on 25 February 2003. As of 2019, the tool is no longer offered by Microsoft for download. An open source alternative is
ttf2eot
. Microsoft PowerPoint 2007 and 2010 also generate .eot files with the '.fntdata

extension when fonts are selected to be embedded in a presentation by the PowerPoint client application. These .eot files can be extracted from the '.pptx' file and used directly on web pages.

Security issues

Critical security update for

Windows Vista Windows Vista is a major release of the Windows NT operating system developed by Microsoft. It was the direct successor to Windows XP, which was released five years before, at the time being the longest time span between successive releases of ...

KB969947 resolves several security issues that "could allow remote code execution if a user viewed content rendered in a specially crafted Embedded OpenType (EOT) font". Such fonts could be embedded in Web sites, including those that host user-provided content.

References

External links

Microsoft Typography - Font Embedding for the WebMicrosoft Typography - Web Embedding Fonts ToolEOT-utils
– open-source free software to make EOT fonts by W3C
ttf2eot
– open-source free software to convert font from TTF to EOT
Compatibility table for support of EOT fonts in browsersW3C Submission describing the formatMinutes of the W3C Fonts Working Group, 23 October 2008MIME registrationGoogle Web Fonts
{{Typography terms Font formats

Overview

Web Embedding Fonts Tool

Security issues

See also

References

External links