font-variant-alternates & @font-feature-values@font-feature-values gives a font's numbered stylistic-set features (ss01–ss20, cv01–cv99, and the single-feature salt, swsh, ornm and nalt) a readable name per font family, so font-variant-alternates can select them by name instead of a raw index. Recursive's ss01 swaps a double-story lowercase "a" for a simplified single-story form, and its ss02 does the same for "g" - both real GSUB Single Substitution data, confirmed by direct byte inspection, not an approximation.
@font-feature-values Recursive {
@styleset { simple-a: 1; simple-g: 2; }
}Same text, same font - only font-variant-alternates differs:
| font-variant-alternates | Sample |
|---|---|
| normal (default forms) | agog gala |
| styleset(simple-a) | agog gala |
| styleset(simple-g) | agog gala |
| styleset(simple-a, simple-g) | agog gala |