Descender is non-negative

Audit code: metrics-descender-nonnegative

Definition

Descender is zero or positive — descending letters (g, j, p, q, y) will sit on the baseline rather than dropping below it. Descender values are conventionally negative (e.g. -200 at 1000 UPM).

How Patens surfaces this

The Patens audit module checks for metrics-descender-nonnegative across five teaching surfaces: the edit-panel inline issue list, the project-wide audit page, the release pre-flight check, the family hub, and the home-page project tile. Every surface shows the same plain-English explanation and links back to this page. This rule is detection-only — there's no automatic fix because the correction is design-dependent (it requires a judgment call about the glyph's intended shape or the font's intended behaviour). The audit message links to the specific glyph or field that needs attention.

Run this check yourself

Patens runs every audit rule live as you draw — including this one. The editor (in private alpha) shows metrics-descender-nonnegative firing on real glyphs, or check your own work from the CLI:

npx patens audit your-project.font.json

Canonical references

Primary literature where this rule is established or explained. Drawn from the open-licensed corpus — browse the full 42-source canonical library or read the research artifact.

OpenType Specification 1.9.1 ↗
Microsoft Typography · 1997 · Microsoft Corporation· § OS/2 — sTypoDescender

sTypoDescender should be negative or zero (descenders sit below the baseline); positive values are nearly always errors.

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