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. The specification germinated at Microsoft, with Adobe Systems also contributing by the time of the public announcement in 1996. The specification continues to be developed actively and is presently migrating to an open format. Because of wide availability and typographic flexibility, including provisions for handling the diverse behaviors of all the world's writing systems, OpenType fonts are used commonly today on the major computer platforms. Contents [hide] 1 History 2 Description 3 Comparison to other formats 4 OpenType support 4.1 Basic Roman support 4.2 Extended language support 4.3 Advanced typography 5 OpenType Feature File (.fea) 6 Layout tags 6.1 Script tags 6.2 Language system tags 6.3 Feature tags 6.4 Baseline tags 7 SING gaiji solution 8 Security issues 9 See also 10 References 11 External links [edit]History

OpenType is intended by Microsoft and Adobe to supersede both the TrueType and the Type 1 («PostScript») font formats. TrueType was developed by Apple Computer and licensed by Microsoft, and PostScript and the Type 1 format were developed by Adobe. Needing a more expressive font format to handle fine typography and exotic behavior of many of the world's written scripts, the two companies combined the underlying technologies of both formats and added new extensions intended to address the limitations. OpenType's origins date to Microsoft's attempt to license Apple's advanced typography technology, «GX Typography,» in the early 1990s. Those negotiations failed, motivating Microsoft to forge ahead with its own technology, dubbed «TrueType Open,» in 1994.[1] Adobe joined Microsoft in those efforts in 1996, adding support for the glyph outline technology used in its Type 1 fonts. The name OpenType was chosen for the combined technologies, and the technology was announced later that year. Adobe and Microsoft continued to develop and refine OpenType over the next decade. Then, in late 2005, OpenType began migrating to an open standard under the International Organization for Standardization (ISO) within the MPEGgroup, which had previously adopted OpenType by reference. The new standard is essentially OpenType 1.4, with appropriate language changes for ISO, and is called the «Open Font Format.» Adoption of the new standard reached formal approval in March 2007 as ISO Standard ISO/IEC 14496-22.[2] It is a free, publicly available standard.[3] By 2001 hundreds of OpenType fonts were on the market. Adobe finished converting their entire font library to OpenType toward the end of 2002. As of early 2005, around 10,000 OpenType fonts had become available, with the Adobe library comprising about a third of the total. By 2006, every major font foundry and many minor ones were developing fonts in OpenType format. [edit]Description

TrueType outlines use quadratic Bézier splines.

CFF outlines use cubic Bézier splines. OpenType uses the general sfnt structure of a TrueType font, but it adds several smartfont options that enhance the font's typographic and language support capabilities. The glyph outline data in an OpenType font may be in one of two formats: either TrueType format outlines in a 'glyf' table, or Compact Font Format (CFF) outlines in a 'CFF ' table. CFF outline data is based on the PostScript language Type 2 font format. The table name 'CFF ' is four characters long, ending in a space character. However, the OpenType specification does not support the use of PostScript outlines in a TrueType Collection font file. For many purposes, such as layout, it doesn't matter what the outline data format is, but for some purposes, such as rasterisation, it is significant. The term «OpenType» doesn't specify outline data format. Sometimes terms like «OpenType (PostScript flavor)», «Type 1 OpenType», «OpenType CFF», or «OpenType (TrueType flavor)» are used to indicate which outline format a particular OpenType font contains. OpenType has several distinctive features: The font character encoding is based on Unicode and can support any script (or multiple scripts at once). OpenType fonts can have up to 65,536 glyphs. Fonts can have advanced typographic features that allow proper typographic treatment of complex scripts and advanced typographic effects for simpler scripts, such as the Latin script used in writing English. Font files are intended to be cross-platform, and can be used without modification on Mac OS, Windows and some Unix systems. If no additional glyphs or extensive typographic features are added, OpenType CFF fonts can be considerably smaller than their Type 1 counterparts. [edit]Comparison to other formats

Compared with Apple Computer's «GX Typography»—now called Apple Advanced Typography (AAT)—OpenType is less flexible in typographic options, but superior in language-related options and support.[clarification needed] OpenType has been much more successful than AAT. There are many more fonts and supporting applications, despite AAT being an older technology. The single-platform nature of AAT and the lack of support from any major software vendor other than Apple itself are both likely factors in this.[citation needed] From a font developer's perspective, OpenType is, for many common situations, easier to develop for than AAT. First, the simple declarative substitutions and positioning of OpenType are more readily understood than AAT's more complex (but powerful) state tables. Second, Adobe's strategy of licensing at no charge the source code developed for its own font development, AFDKO (Adobe Font Development Kit for OpenType), allowed third-party font editing applications such as FontLab and FontMaster to add support with relative ease. Although Adobe's text-driven coding support is not as visual as Microsoft's separate tool, VOLT (Visual OpenType Layout Tool), the integration with the tools being used to make the fonts has been well received. Another difference is that an OpenType support framework (such as Microsoft's Uniscribe) needs to provide a fair bit of knowledge about special language processing issues to handle (for example: Arabic). With AAT, the font developer of an AAT font has to encapsulate all that expertise in the font. This means that AAT can handle any arbitrary language, but that it requires more work and expertise from the font developers. On the other hand, OpenType fonts are easier to make, but can only support complex scripts if the application or operating system knows how to handle them. Prior to supporting OpenType, Adobe promoted multiple master fonts and expert fonts for high-end typography. Multiple master fonts lacked the controls for alternate glyphs and languages provided by OpenType, but provided smooth transitions between styles within a type family. Expert fonts were intended as supplementary fonts, such that all the special characters that had no place in the Adobe Standard Encoding character set – ligatures, fractions, small capitals, etc. – were placed in the expert font instead. Usage in applications was tricky, with, for example, typing a 'Z' causing the 'ffl' ligature to be generated. In modern OpenType fonts all these glyphs are encoded with their Unicode indices and selection method (i.e. under what circumstances that glyph should be used). [edit]OpenType support

[edit]Basic Roman support OpenType support may be divided into several categories[citation needed]: virtually all applications and most modern operating systems have basic Roman support and work with OpenType fonts just as well as other, older formats. What is of particular interest apart from basic Roman support is: Extended language support through Unicode, support for «complex» writing scripts such as Arabic and the Indic languages, and advanced typographic support for Latin script languages such as English. Amongst Microsoft's operating systems, OpenType TT fonts (.True Type Fonts) are backward compatible and therefore supported by all Windows versions starting with Windows 3.1. OpenType PS fonts (.OTF) are supported in all Windows versions starting with Windows 2000; Adobe Type Manager is required to be installed on Windows 95/98/NT/Me for basic Roman support (only) of OpenType PS fonts. [edit]Extended language support Extended language support via Unicode for both OpenType and TrueType is present in most Windows applications (including Microsoft Office Publisher, most Adobe applications, and Microsoft Office 2003, though not Word 2002), and many Mac OS X applications, including Apple's own such as TextEdit, Pages and Keynote. OpenType support for complex written scripts has so far mainly appeared in Microsoft applications in Microsoft Office, such as Microsoft Word and Microsoft Publisher. Adobe InDesign provides extensive OpenType capability in Japanese but does not directly support Middle Eastern or Indic scripts— though a separate version of InDesign is available that supports Middle Eastern scripts such as Arabic and Hebrew. Undocumented functionality in many Adobe Creative Suite 4 applications, including InDesign, Photoshop and Illustrator, enables Middle Eastern, Indic and other languages, but is not officially supported by Adobe, and requires third-party plug-ins to provide a user interface for the features. [edit]Advanced typography Advanced typographic support for Latin script languages first appeared in Adobe applications such as Adobe InDesign, Adobe Photoshop and Adobe Illustrator. QuarkXPress 6.5 and below (Quark, Inc.) were not Unicode compliant. Hence text that contains anything other than WinANSI/MacRoman characters will not display correctly in an OpenType font (nor in other Unicode font formats, for that matter). However, Quark offers support similar to Adobe's in QuarkXPress 7, which shipped in May 2006. Corel's CorelDRAW does not support OpenType typographic features, either. Mellel, a Mac OS X-only word processor from Redlers, claims parity in typographic features with InDesign, but also extends the support to right-to-left scripts. As of 2009, popular Windows word processors do not support advanced OpenType typography features. Advanced typography features are implemented only in high-end desktop publishing software. However, the text engine from Windows Presentation Foundation, which is a managed code implementation of OpenType is the first Windows API to expose OpenType features to software developers, supporting both OpenType TrueType, and OpenType CFF (Compact Font Format) fonts. It supports advanced typographic features such as ligatures, old-style numerals, swash variants, fractions, superscript and subscript, small capitalization, glyph substitution, multiple baselines, contextual and stylistic alternate character forms, kerning, line-level justification, ruby characters etc. WPF applications automatically gain support for advanced typography features. OpenType ligatures are expected to become accessible in Microsoft Office Word 2010, having been demonstrated in the Technical Preview released in May 2009.[4] Windows 7 introduced DirectWrite, a hardware accelerated native DirectX API for text rendering with support for multi-format text, resolution-independent outline fonts, ClearType, advanced OpenType typography features, full Unicode text, layout and language support and low-level glyph rendering APIs.[5] On Mac OS X, AAT-supporting applications running on Mac OS X 10.4 and later, including TextEdit and Keynote, get considerable OpenType support. Apple's support for OpenType in Mac OS X 10.4 included most advanced typographic features necessary for Latin script languages, such as small caps, oldstyle figures, and various sorts of ligatures. It did not yet support contextual alternates, positional forms, nor glyph reordering as handled by Microsoft's Uniscribe library on Windows. Thus, Mac OS X 10.4 did not offer support for Arabic or Indic scripts via OpenType (though such scripts are fully supported by existing AAT fonts). Mac OS X 10.5 has improved support for OpenType and supports Arabic OpenType fonts. Bitstream Panorama, a line layout and text composition engine from Bitstream Inc., provides complete OpenType support for compact and standard Asian fonts, Arabic, Hebrew, Indic, Thai and over 50 other worldwide languages. The application supports key OpenType tables required for line layout, such as BASE, glyph definition (GDEF), glyph positioning (GPOS), and glyph substitution (GSUB). Panorama also offers complete support for advanced typography features, such as ligatures, swashes, small caps, ornaments, ordinals, superiors, old style, kerning, fractions, etc. In free software environments such as Linux, OpenType rendering is provided by the FreeType project, included in free implementations of the X Window System such as Xorg. Complex text handling is provided either by pango or Qt. The XeTeX system allows TeX documents to use OpenType fonts, along with most of their typographic features.