Charts · 24

The anatomy of a letter

Every argument about a typeface is really an argument about four or five small decisions: how open the counter is, how wide the aperture is, whether the crossbar is level, what the leg of the R does. Once the parts have names the argument gets shorter. Four specimens, their parts labelled, and their horizontal lines measured from the real font rather than drawn from a textbook.

gEarBowlCounterLinkLoop

Notes

The metric lines are measured in your browser with measureText at 400px after the font loads: x-height from a lowercase x, cap height from an H, ascender from an h, descender from a p, and the overshoot as the difference between a round o and a flat x. Overshoot is the one that surprises people: a circle that stops exactly at the x-height line looks short, so type designers draw round letters a few thousandths of an em taller, and the measured value here is that font’s actual choice. The pointers are found in the ink rather than typed in: the glyph is rasterised once, then each part names a rule that locates it (the ear is the rightmost ink in the top band, a counter is the middle of an enclosed white run, the leg is the lowest ink on the right), with the bands expressed as fractions of that glyph’s own ink box so the same rule holds in any font. Every resolved point except the counters is snapped onto ink, so a pointer cannot float in the gap. Every name used is standard (Bringhurst; Cheng; the Type Nomenclature ISO draft). The classification cue on the e is real and useful: a slanted crossbar marks a Venetian or humanist roman, a level one a Garalde or later, which is chart 04’s first branch. Sources: Bringhurst, The Elements of Typographic Style; Cheng, Designing Type; Unger, Theory of Type Design.