Italic – The Twelve Days of Ax‑mas

On the fifth day of ax-mas, we’re exploring: the Italic ital axis.

This rounds out the five gold Registered Axes of Variable Fonts—though while Italic seems like it should be the most straightforward on first glance, I think it might be the most confusing. Yesterday I wrote about when to use the Slant axis instead of the Italic axis.

Another option, even if your family has an italic, is to use neither axis.

Using neither Italic or Slant

If you are porting an existing family to a Variable Font structure, or your new design is fairly conventional—that is, maybe there is Width and Weight, but you don’t care about the end typographers modifying the angle of the italic—one option is to have two Variable Font files.

  • One file is for the regular.
  • One file is for the italic.

Both have the same axis, and the same range, but don’t need to have compatible outlines.

To me, if your italic is designed with a specific angle in mind only, and you don’t want people modifying it, this option is worth considering.

You make a small concession: your family is two font files, not one, that behave like many font files, and avoid some complexity for yourself and for end users.

The complexity for end users is that the Italic axis is has some ambiguities that are actively being resolved in the documentation.

Is Italic a range?

One open question is more in the CSS ream, regarding how web developers access the Italic and Slant axis in fonts that have both. The more important one for type designers making Variable Fonts:

Is the Italic axis a range? Is the Italic axis an off/on (0 or 1) switch, or does it have a range of values (from 0 to 1)? The Italic axis doesn’t represent angle, so can something really be even more italic? Can you have a 0.5 value for the Italic axis, and if so, what does “half italic” even mean?

In my interpretation, the answer is yes, although I don’t think this was intended. Or put another way, in a literal reading, the answer is yes, but in a more generous reading, the answer is no, so it probably shouldn’t be used that way.

A lot of this came to my attention from reading the ongoing discussions on GitHub about how this can be clarified, so it’s certainly a known ambiguity. Here is the summary in question:

Description: Used to vary between non-italic and italic.

Valid numeric range: Values must be in the range 0 to 1.

Scale interpretation: A value of 0 can be interpreted as “Roman” (non-italic); a value of 1 can be interpreted as (fully) italic.

Emphasis mine. If the valid numeric range was “Values must be 0 or 1, that would be hard to argue with. Combined with, “a value of 1 can be interpreted as (fully) italic”—as in there is something less than fully italic—also implies to me that it is a range—although I still am left guessing what exactly “a little italic” is.

Tomorrow, we’ll look at two ways type designers have already interpreted (or played with) this ambiguity in real fonts, and move onto Custom Axes.

Until next time,