What is OpenType?
OpenType is a cross-platform font format created by the combined efforts of Microsoft and Adobe. In addition to allowing you to use the same font file on your Mac or PC, using OpenType means you no longer have to make the sometimes confusing decision between whether to use TrueType or PostScript. Enhanced OpenType fonts are often distinguished by the designation "Pro."
How is Enhanced OpenType Different from TrueType and Postscript?
Basic Opentype, TrueType and PostScript fonts usually contain standard character sets with a maximum of 256 glyphs. The OpenType format, however, is capable of supporting expanded character sets containing thousands of characters or glyphs. This allows for the inclusion of many extra features such as ligatures, small caps, swashes, and ornaments within a single font. In addition to providing layout features for good typography, OpenType offers support for greater linguistic support. Pro fonts can add a full range of accented characters to support central and eastern European languages, such as Turkish and Polish. Some Pro fonts also contain Cyrillic and Greek character extensions in the same font.
What Programs Use OpenType?
OpenType-compatible programs such as Adobe CS products and the most recent releases of Quark Xpress can access OpenType features. However, users without full OpenType support can substitute OpenType fonts for TrueType or PostScript, may not necessarily have access to some features, or all the glyphs in the font. For an up-to-date listing of OpenType-savvy applications and which features they support, check here: http://www.typotheque.com/fonts/opentype_feature_support/
Using OpenType and accessing its features
In Adobe CS products, features are accessed through the Type Palette [window/ type and tables/ character]. The small arrow in the upper right shows options for small caps, ligatures, etc., and, in the OpenType sub-menu, you can access other features such as contextual alternates (which is turned on by default), ornaments, swash, etc. To activate a feature, click on it (a check mark will show it has been activated); clicking it again will turn it off. Features that are grayed-out or in brackets are not available. You can apply features to a single character or to an entire document, depending on what is selected when the feature is checked. Even among applications that do support OpenType features, there is some disparity between applications in what features are supported. Another way of accessing glyphs is through the glyph palette. In Adobe CS products, this is located in windows/ type and tables/ glyphs. The glyph palette can show you all the characters in a font, which glyphs are accessed by a particular layout feature or available alternates to a selected glyph. For more information of how to use OpenType in Adobe CS programs, check here:
OpenType fonts for OSX
Some enhanced OpenType fonts may show up in an odd place in the font menu in various versions of Mac OSX when using Adobe CS products. If a font shows up at the bottom of your font menu, you May try unistalling the font, running it through OFT File Typer (a free utility), and reinstalling the font. You can download OTF File Typer here: OTF File Typer. To be sure all OpenType features function properly for Adobe CS application, it is best to install the fonts into the: MacHD->Library->Application Support->Adobe->Fonts folder.
OpenType Feature Definitions
Lining Numerals (lnum)
Modern style numerals where all figures are of the same height and rest on the baseline.
Oldstyle Numerals (onum)
Style of Arabic Numerals where the characters appear at different positions and heights.
Proportional Numerals (pnum)
Numerals spaced in varied widths depending on the character.
Tabular Numerals (tnum)
Monowidth numerals where all figures have identical widths.
Superior Figures (sups)
Letterforms that replace lining or oldstyle figures primarily for footnote indication and French abbreviations.
Scientific Figures (sinf)
Letterforms which sit lower than the standard baseline, primarily for chemical or mathematical notation.
A function that substitutes either upper or lowercase characters with Subscript characters (letters or numerals) that are positioned lower than the text on the line.
This features creates Superscripted glyphs when using ordinal numbers such 1st or 2nd as well as the Spanish Segunda/Segundo.
A feature that creates fractions in place of common slash characters.
The top part of a fraction. This feature substitutes designed numerator glyphs for numbers.
The bottom part of a fraction. This feature substitutes designed numerator glyphs for numbers.
Slash Zero (zero)
A character useful in cases where the figure zero might be confused with the letter O.
A ligature is a special character that combines two (or sometimes three) letters into a single character. This feature automatically substitutes ligature glyphs for letter combinations where characters might otherwise "collide". Common ligatures are: fi, fl, ffi, ffl.
Discretionary Ligatures (dlig)
Preferred Ligatures for typographical purposes and user defined ligatures used for special effect such as ct, st, Th
Contextual Ligatures (clig)
a ligature glyph which is preferred for typographical purposes. This feature will substitute specific combination of letters in a script font which overlap awkwardly with a more pleasing combination.
Historical Ligatures (hlig)
Ligatures that were in common use in past, but appear out of date such as the long s combinations.
Case-Sensitive Forms (case)
Feature that positions punctuation marks to work better with all caps or lining figures and changes oldstyle figures to lining figures.
Capital Spacing (cpsp)
Feature that adjusts spacing for use with all-capital text.
Small Caps (smcp)
Proportional characters that are the same weight as the rest of the font and a bit wider proportionally from the Capitals.
Caps to Small Caps (c2sc)
Feature that replaces Capitals with Small Capitals.
Ornate alternate Capitals.
Stylized letterforms with extended strokes.
Contextual Swash (cswh)
Feature that applies swash characters contextually or in a specified context.
Contextual Alternates (calt)
Feature that applies alternate variations contextually or in a specified context.
Stylistic Alternates (salt)
Alternate glyphs for a purely esthetic effect.
Historical Forms (hist)
Letterforms that were in common use in the past such as the 'long s'.
Stylistic Sets (ss01-ss20)
A set of stylistic alternate characters that correspond to portions of the character set.
Local Feature (locl)
Characters that are language specific or used by individual communities.
Access all Alternates (aalt)
A feature that makes all variations of a selected character accessible.
Ornamental glyphs or Dingbats.
The total number of glyphs or characters contained in a Pro OpenType style font.
Diacritics and Characters needed for latin languages including english. See chart for other languages.
Diacritics and Characters needed for latin languages not including english. See chart for other languages.
Latin Extended Additional
Diacritics and Characters needed for extended Latin languages. See language coverage chart.
Central European (CE)
Diacritics and Characters needed for Central European languages. See Latin Extended A below.
Characters and Diacritics needed for Cyrillic.
Characters and Diacritics needed for Greek.
For fonts that contain either Central European, Cyrillic or Greek character sets, the full range of these languages is listed below.
Latin Extended-A (Central European):*
Azerbaijani (also requires some glyphs from Latin Extended-A)
Pinyin (Mandarin Romanization)
Latin Extended Additional:*
IPA Extentions: †
International Phonetic Alphabet
Central Siberian Yupik
Old Church Slavonic
* Also requires Latin-1.
** Also require Greek.
† Also require Latin-1 & Greek.
‡ Also require Cyrillic.
OpenType Installation Instructions