Design Nomenclature / Type
Variable font
Also called VF, OpenType Variations, OpenType 1.8
An OpenType font holding a continuous design space rather than fixed instances: master outlines plus deltas, interpolated at render time along one or more axes. One file can replace a dozen static weights at a fraction of the bytes, and gives every value between the masters — 437 as readily as 400 or 500.
In practice
Named instances are the safe ground; arbitrary values between them are legitimate but unrehearsed, and a face whose design space has thin spots will show it. Set font-variation-settings only via the high-level properties where they exist.
Not to be confused with
- OpenTypeThe font format in universal use since the late 1990s, holding either TrueType or PostScript/CFF outlines in one file, Unicode-mapped, cross-platform, and — the part designers care about — carrying layout tables. GSUB substitutes glyphs, GPOS positions them; between them they drive ligatures, small caps, figure sets, alternates and kerning.
- StressThe angle of the line joining the thinnest points of a round stroke — a fossil of the broad-nibbed pen's angle. Humanist and garalde faces have it inclined to the left; transitionals bring it near vertical; didones make it exactly vertical. Most sans faces have no meaningful stress at all, being close to monoline.