alternate figures

Consider the context

Though we think of a font as a set of char­ac­ters with a uni­form visual appear­ance, the gen­e­sis of these char­ac­ters is any­thing but uni­form. Our writ­ing sys­tem brings together char­ac­ters that were orig­i­nally hand­writ­ten by peo­ple in dif­fer­ent coun­tries, in dif­fer­ent cen­turies. To achieve a uni­form appear­ance, a type designer has to har­mo­nize these dis­parate forms.

Our upper­case alpha­bet came from the inscrip­tional cap­i­tals of the Romans. Our low­er­case alpha­bet came from the Euro­pean uncial alpha­bets of the Mid­dle Ages, which them­selves evolved from scribal approx­i­ma­tions of the upper­case alpha­bet.

But our fig­ures were invented in India. They spread west through the influ­ence of Per­sian and Arab math­e­mati­cians. Tra­di­tion­ally they were known as Ara­bic numer­als, but lat­terly as Hindu-Ara­bic numer­als. Indic and Ara­bic lan­guages, of course, look very dif­fer­ent from Euro­pean lan­guages. Thus, fig­ures have always pre­sented a chal­lenge for type design­ers, as they rely on shapes that are found nowhere in the upper­case and low­er­case alpha­bets.

Type design­ers have met this chal­lenge by devis­ing sets of alter­nate fig­ures, intended for dif­fer­ent typo­graphic con­texts. Three things to know in advance:

  1. It’s never wrong to use the default fig­ures in your font—namely, the ones you get when typ­ing the keys 0–9. Those are put in the default posi­tion because they’re intended to work well across a range of con­texts.

  2. Not every font has every set of alter­nate fig­ures listed here. Alter­nate fig­ures are added based on the type designer’s impres­sion of how the font will be used and whether the alter­nates will be use­ful.

  3. If alter­nate fig­ures are included in your font, they’ll be imple­mented as OpenType features. The caveats there also apply, espe­cially per­tain­ing to soft­ware sup­port.