OpenType® overview

OpenType is a font format developed jointly by Microsoft and Adobe as an extension of Apple’s TrueType font format. The OpenType 1.0 font specification was released in 1997. Since that time Adobe and Microsoft have continued to work together updating and refining the specification. Several other companies, including Apple and Monotype, have also contributed to the specification over the years. Currently, every major font foundry and most minor ones are developing fonts in OpenType format.

OpenType provides several advantages over older font technologies:

  • Larger glyph limit (64k)
  • Cross-platform support (Win and Mac)
  • Support for both PostScript Type 1 or TrueType outlines
  • Support for advanced typographic features

OpenType, like TrueType, is based on Unicode, the system for encoding all of the world’s writing systems. OpenType fonts can potentially contain many thousands of characters. This means that an OpenType font may contain multiple alphabets (such as Latin, Greek, and Cyrillic; or kanji, kana, and romaji for Japanese use). OpenType fonts can also include typographic refinements such as true small caps, different styles of figures, and extensive sets of ligatures and alternates, as well as complete sets of accented characters and diacritical marks. Different applications have differing levels of support for all the OpenType features.

OpenType version 1.4 was contributed to ISO and became the foundation for the development of ISO/IEC 14496-22 “Open Font Format” standard. The standard was published in 2007, and is now freely available for download from ITTF website. OpenType version 1.6 is identical to the “Final Draft International Standard” version of ISO/IEC 14496-22 FDIS “Open Font Format” (second edition).

To learn more about OpenType fonts, refer to the most recent version of the OpenType specification and the FAQ that follows.

Frequently asked questions about OpenType

What is OpenType and how does it relate to Type 1 and TrueType?

OpenType, also known as TrueType Open version 2, is an extension of Microsoft’s TrueType Open format, adding support for Type 1 data. An OpenType font can have Type 1 data only, TrueType data only, or both. The Type 1 data can be rasterized by a Type 1 rasterizer (such as Adobe Type Manager) if installed, or converted to TrueType data for rasterization by the TrueType rasterizer. The exact rasterization behavior will be a function of the rasterizers present in the system, and user preference.

This font format is a superset of the existing TrueType and Type 1 formats, which is designed to provide great support for type in print and on-screen. In addition, the subsetting and compression technology of OpenType makes the OpenType initiative especially relevant to the Internet and the World Wide Web, since it allows for fast download of type.

What is the benefit of the OpenType initiative to the end-user?

So far as customers are concerned, fonts just work. OpenType handles all fonts with a unified registry, which means that both Type 1 and TrueType fonts will be reliably supported across all platforms. In addition, by working together Adobe and Microsoft will drive innovations in quality and on-screen support, resulting in better more viewable fonts for customers.

What will happen to existing Type 1 and TrueType fonts?

From a customer perspective, all existing Type 1 and TrueType fonts will be supported by the OpenType initiative. As part of the agreement between Microsoft and Adobe, however, Adobe will convert popular existing Type 1 fonts to the new OpenType format, and Microsoft and Adobe will jointly promote and develop new OpenType fonts.

If I’m an existing user of one font type or the other, what will I do?

You should continue working as you always have. OpenType will seamlessly support both TrueType and Type 1 fonts.

What does this mean for all the type vendors who have large libraries of fonts? Are they obsolete?

Font vendors don’t need to worry. Their existing fonts just work.

Will all data types continue to be supported by the OpenType initiative?

Yes. Because the OpenType font format is a superset of Type 1 and TrueType font technologies, it will continue to support both standards. In the future, both Microsoft and Adobe will invest in promoting and developing OpenType fonts, and as part of the agreement between Microsoft and Adobe, Adobe has agreed to convert some of the existing popular Type 1 fonts to the new format.

Can an OpenType font contain TrueType outlines?

Yes, OpenType fonts can contain either PostScript Type 1 or TrueType outlines. All Microsoft Windows fonts contain TrueType outlines.

What is an OpenType CFF font?

An OpenType CFF font is an OpenType font which contains PostScript Type 1 outlines.

Why is my OpenType font listed as a TrueType font by my application?

Different applications have different ways of determining if a font is OpenType. Most look for specific tables within the font. In some cases, a font may be OpenType, but a particular table is missing and the application may consider it a TrueType font.

What applications support OpenType features?

Desktop publishing applications such as Adobe InDesign and QuarkXpress support the largest number of OpenType features. Adobe Photoshop and Adobe Illustrator support many features. Support for common OpenType features is also being added to Microsoft Publisher and Microsoft Word in Office 14.

Can I convert old fonts to OpenType format?

The best thing to do is to contact the font vendor who created the original fonts.

How many glyphs are allowed in an OpenType font?

64,000 glyphs

Can the same font file be used on both Mac and Windows?


Why did Adobe and Microsoft decide to end the font wars?

Both companies realized that merging Type 1 and TrueType is the best solution for customers because now both font standards will be seamlessly supported on the Windows and Macintosh platforms. Additionally, OpenType will allow the industry to drive font innovation, display quality, and print output into new publishing arenas, such as the Web.

What does the OpenType initiative mean to Adobe’s font business?

The OpenType initiative represents a new opportunity for Adobe to expand its font business into the Windows market because Type 1 fonts will now work out of the box on all Windows systems. In addition, because Adobe will license TrueType technology, it will now be able to develop and market TrueType fonts.

What will Adobe and Microsoft be cross-licensing?

Both companies will license their respective font rasterizers, production tools, and conversion software.