The Secret Life of OpenType Features

For more than 20 years, designers have been working with Type1 fonts that only allowed a limited amount of characters to exist in one font (namely, 256 — most of which could be selected in one key stroke). However, the technical demands on typography in a global context have increased. International standardization (Unicode) and the desire to improve quality and convenience across different platforms (Windows, Mac and Linux) has brought about a major change in font technology: the development of the OpenType format. Unlike its predecessor, OpenType allows thousands of glyphs — Latin characters with and without accents, Greek and/or Arabic, sets of figures, arrows and symbols or elaborate swashes — to be integrated into a single font.

OpenType Charactures and Figures

Left, an overview of all the characters and figures — the glyphs — of two separate Type1 fonts with standard characters (green) and smallcaps characters (blue). Shown at right, an OpenType Pro version of the same font including the glyphs of the Type1 versions as well as additional figure and arrow sets and accented characters for extended language support.








As a consequence, not all characters can be reached in one key stroke of the keyboard and a method is needed for the user to control the choice of letter variant or type of figure. This intelligence is integrated into the OpenType font and is called glyph substitution — a technology that is now supported by all professional design and layout programs and an increasing number of programs in the office environment. Glyph substitution enables the application of particular characters, numbers or symbols, depending on the features the user chooses. Exactly which features are available vary from font to font and depending on the design of the typeface, there may be alternate versions for ‘a’ while another typeface offers more than one ‘g’.

As a graphic designer as well as a type designer, my insight into both worlds has led me to conclude that type designers are comfortable with the potential and practical use of OpenType features while many graphic designers are still hesitant to use them. There is a lot of agreement on this from my colleagues in both camps, so I thought I’d give a few helpful examples here of what one can expect from many of today’s OpenType fonts.

For starters, access to the activation and deactivation of features is not organized consistently in the dominant graphic design programs (yes, all of them from Adobe — there seems to be a lack of competition). To reach them sometimes requires unbearable travel through various sub menus, making it cumbersome for users to get acquainted with using them. The level of support is also not consistent, causing insecurity over whether to purchase a typeface license with a desired feature that is not supported across the board. In InDesign CS2 through CS5 for example, Stylistic Alternates are not supported while they are in Illustrator and Photoshop. The reverse is true for Stylistic Sets 1-20 which are supported by ID but not by PS or Ai.

OpenType Features in Adobe CS4

This is where you can access OpenType features in Adobe’s CS4 Illustrator and Photoshop. Illustrator has a handy panel that allows easy access to the most common features via clickable icons.








InDesign OpenType Support Features

The application with one of the best feature supports — even if somewhat hidden away in sub menus — is InDesign. All functions that actually use OpenType features are marked in gray. If the name of a feature is written within brackets, it means that the chosen font does not have that feature included. (Note: If you choose ‘Small Caps’ in a font that does not have any, InDesign will simulate the effect by scaling down characters according to your settings in preferences. The same is true for ‘Superscript’ or ‘Subscript’ in the first pop-up menu. If available, choose ‘Superscript/Superior’/‘Subscript/Inferior’ in the second menu).















All Caps in Opentype

The ‘All Caps’ does not only turn any letter into uppercase but it also will apply case sensitive forms: see how the parentheses is moved slightly upward to stand aligned vertically to the all-caps text.






Small Caps OpenType Feature

This feature speaks for itself – but only works well if the font has small caps.





OpenType: Ligatures

The most commonly used glyph substitution feature, switched on by default, is the one for Ligatures. The less common ones — ‘Discrete Ligatures’ or oldstyle ligatures (‘Historical Ligatures’) are however, switched on manually. (Beware: In InDesign any of the ligatures feature is automatically deactivated when the value for tracking is ‘too’ high or low. This is different for every typeface).





Discretionary Ligatures

Ligatures that might be obtrusive in the body text are switched on with this feature.




Ordinals + Old Style Figures, OpenType

This is an example of two features applied together.




OpenType: Swashes

Swashes can be fun: look at the ‘T’, ‘y’, ‘e’, as well as ‘S’ and ‘g.’




OpenType: Contextual Alternates

This is an unusual feature for it allows contextual exchange of letter variants. This typeface (FF Duper) for example has three versions of each letter that are applied depending on which letter follows/precedes the current one. Take a closer look at ‘SEE ME???’ where all occurrences of ‘E’ differ. This feature is switched on by default in ID, Ai and PS.





OpenType: Stylistic Alternates

The Stylistic Alternates may be one of the most interesting addition to any typeface. You can change the expression of a word, headline or entire book page by exchanging only a few letters. Type designers find it a convenient way to expand the versatility of an OpenType font. MPF Realist has an alternative ‘I’, ‘a’, ‘b’, and ‘g’, and round variants of all punctuation marks assigned to Stylistic Alternates. (To make sure that the exchange of letters works in InDesign as well as Illustrator or Photoshop, some type foundries put the same functionality in Stylistic Alternates as well as Stylistic Set 1)






Opentype: Stylistic Set 2

If a font has more than one alternative version of a character — notice ‘a’ and ‘y’ — it can be triggered via Stylistic Sets. (Stylistic Sets are not accessible in Photoshop or Illustrator.)





OpenType: Stylistic Set 4

Stylistic Sets don’t always need to contain letter variants. This particular one turns combinations of brackets and numbers into cameo figures in containers with corresponding shapes.





OpenType: Superscript/Superiors



OpenType: Subscript/Inferiors




OpenType: Fractions

Even non-standard fractions, subscript and superscript figures have become a standard functionality for some type foundries.





OpenType: Tabular Lining FIgures



OpenType: Proportional Lining FIgures


OpenType: Proportional Old-Style


OpenType: Old-style Figures

Modern OpenType fonts often have various figure sets to choose from: tabular, oldstyle — see Myriad’s oldstyle figures above! — lining and proportional lining. Depending in what context your figures are used, you might want to adjust its style: small caps and lowercase, for example, go well with oldstyle figures. If your text is only caps, go for lining figures.










More Type Resources for Graphic Designers

4 thoughts on “The Secret Life of OpenType Features

  1. olafdruemmer


    is incorrect and has been forever for Type 1 fonts, like a few other details:
    – they never contained characters, just glyphs and names identifying them
    – they also contained encodings that mapped numbers between 0 and 255 to glyph names (and thus the respective glyph)
    – they could always contain any number of glyphs
    – an encoding was limited to one range of values form 0 to 255
    – within the same PostScript code using the font (and as a consequence in any program using Type 1 fonts) one could always use more than 256 glyphs – but one had to switch from one encoding to to a different encoding (which is a very normal operation in PostScript)
    – PostScript fonts never had any information about keystrokes in them (not even named encodings like MacRoman or WinAnsi) – that was up to the application making use of the font, and typiclly an application used the current keyboard setup to silently map keystrokes through encodings to codepoints that that ended up calling the right glyph (if present – it could easily happpen that certain characters one could reach through a keystroke – let’s say, a German umlaut – were not present in the form of glyphs in the given font; another example would be upper case only fonts, where the lowercase characters may or may not have been mapped to their upper case equivalent; and then there were and are symbolic fonts where glyohs can be reaxhed through the keyboard but the relationship between keystroke and glyph is completely arbitrary, just think Type 1 ZapfDingbats)

    It is true though that OpenType makes life easier when it comes to using more extended sets of glyphs. Nevertheless, this is not something introduced for the first time by OpenType but became possible already to a substantial degree with TrueType (20 years ago, TrueType was Apple’s and Microsoft’s reaction to Type 1 being encrypted and difficult to make/use/process/output for companies not paying licensing feees to Adobe or not using Adobe technology… – whereas Type 1 has been around for about 27 years already).

    Because of this OpenType was actually “invented” based on TrueType data structures. Whereas TrueType could already handle other scripts (Greek, Cyrilic, Asian scripts, …) OpenType introduced a number of features that made control over which actual glyph was to be used when possible/easier (like shape variations of the same glyph, first and last characters in words in languages like Arabic or to a lesser degree Hebrew).


  2. olafdruemmer

    Hmm – editing ones own comments not possible…? And no option to preview post? WordPress can do much better than that….

    The previous comments was supposed to beginas this (and use non-italoc text for the main portion of the text):


    Type1 fonts that only allowed a limited amount of characters to exist in one font (namely, 256 — most of which could be selected in one key stroke).

    is incorrect and has been forever for Type 1 fonts, like a few other details:

  3. Martin Wenzel Post author

    Hi Olaf,

    it’s obvious you are a keen observer and writer, but my intention was to give readers — people who use fonts as opposed to people that make fonts — some examples what design related attributes can commonly be found in modern OpenType fonts.

    – You are correct when you point out that “glyph” is the accurate term for the representation of a character, though they are commonly referred to as characters. I’ve used the terms interchangeably because it has no bearing on the explanation of the application of OpenType features.

    – technically you could have more than 255 glyphs in a Type1 font, but practically you would not. I’ve been designing and developing fonts – referring to the technical aspect of the production process – since 1991 and all the foundries I’ve worked together with did not exceed the amount in question in text typefaces. When for example, additional glyph variants, different figure sets and/or the support of non-western languages were called for, these would be included in an additional font.

    – you make a key point when you say that Open Type makes life easier because that is actually the point of the post here – to assist designers in the use of fonts. The technical points you describe, though sound, are not I feel, relevant to the intended audience.

    But certainly, thanks for pointing out how intricate the subject matter can become 🙂

    Regards, Martin

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