Open­Type is a font for­mat in­vented in the 1990s by Mi­crosoft and Adobe, and later adopted by Ap­ple. A ma­jor goal of Open­Type was to pro­vide bet­ter sup­port for in­ter­na­tional lan­guages and writ­ing sys­tems than pre­vi­ous for­mats (Post­Script and True­Type).

To do this, Open­Type in­cludes lay­out fea­tures—com­monly known as Open­Type fea­tures—that al­low fonts to spec­ify al­ter­nate let­ter­forms, and rules for how they should be in­serted into the text. These fea­tures are manda­tory for han­dling lan­guages like Ara­bic and Urdu.

They’re not manda­tory in Eng­lish. But as a side ef­fect, Open­Type lay­out fea­tures have al­lowed type de­sign­ers to add lux­u­ries to their fonts—like al­ter­nate fig­ures, small caps, lig­a­tures, or­di­nals, and frac­tions—that had pre­vi­ously been dif­fi­cult or im­pos­si­ble. That’s the good news.

The bad news is that merely se­lect­ing an Open­Type font doesn’t make its fea­tures avail­able. Rather, your type­set­ting pro­gram also has to sup­port the fea­tures you want to use. Even though many Open­Type-en­hanced fonts are avail­able to­day, soft­ware com­pa­nies have been slow to up­grade their applications.

This bit of back­ground just sets the stage for the an­noy­ing truth—that Open­Type fea­tures can add a lot of ty­po­graphic so­phis­ti­ca­tion to your doc­u­ment, but you can only use a given fea­ture if it’s sup­ported by both the font and the application.

If you still want to use Open­Type fea­tures, some tips:

1. De­sign­ers of pro­fes­sional fonts (see font rec­om­men­da­tions) will have down­load­able spec­i­men sheets that show you which Open­Type fea­tures are sup­ported by their fonts.

2. All ma­jor desk­top web browsers sup­port Open­Type fea­tures. Sup­port is spot­tier among mo­bile web browsers.

3. The best Open­Type fea­ture sup­port is found in pro­fes­sional page-lay­out ap­pli­ca­tions like Adobe In­De­sign, Adobe Il­lus­tra­tor, and Quark Xpress.

4. Re­cent ver­sions of Mi­crosoft Word (≥ 2010 for Win­dows, ≥ 2011 for Mac) sup­port a lim­ited set of Open­Type fea­tures (lig­a­tures, al­ter­nate fig­ures, and styl­is­tic sets). But Ex­cel and Power­Point don’t sup­port any. If you think this is ironic and a lit­tle sad given that Mi­crosoft in­tro­duced the Open­Type for­mat in 1996, me too.