Design Nomenclature / Systems & Spec
WCAG
Also called Web Content Accessibility Guidelines, WCAG 2.2, WCAG 2.1, W3C accessibility guidelines
The W3C's Web Content Accessibility Guidelines: testable success criteria filed under four principles and graded A, AA, or AAA. Conformance is claimed per page, against a stated version, and each level subsumes the ones below. It measures conformance — not whether disabled people can actually complete the task.
In practice
Law by proxy: Section 508 and EN 301 549 both incorporate WCAG 2.x Level AA by reference, which is where most of its legal force comes from.
Not to be confused with
- Level AAThe middle WCAG conformance level, and the one policy nearly always specifies. Requires every Level A and Level AA criterion: text contrast 4.5:1, or 3:1 for large text — 18.66px bold or 24px regular; non-text contrast 3:1; reflow to 320 CSS px; and, from 2.2, target size 24×24 CSS px.
- APCAA contrast model developed for WCAG 3 that reports a polarity-aware lightness contrast value, Lc, rather than a ratio, and factors in text size and weight. It exists because WCAG 2.x contrast handles dark backgrounds poorly. It is a candidate in a working draft — nothing conforms to APCA, and it replaces no shipped criterion.