a11y teacher edition W3C WCAG 2.2 & WCAG 3.0 draft reference
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Translating W3C Standards for Designers, Developers, QA & Product teams

SC 3.3.3 Level AA Understandable

Error Suggestion

WCAG 2.2 success criterion • Guideline: Input Assistance

Tier 1 ยท The normative floor

Baseline compliance

What the normative text of WCAG 2.2 requires, and nothing more. Only a failure of this tier is a WCAG failure.

The bare minimum

If an input error is automatically detected and suggestions for correcting it are known, the suggestions are provided, unless that would compromise the security or purpose of the content.

Normative text

Verbatim from WCAG 2.2, W3C Recommendation 12 December 2024. Underlined terms are defined below.

If an input error is automatically detected and suggestions for correction are known, then the suggestions are provided to the user, unless it would jeopardize the security or purpose of the content.

Known failures

These fail this criterion or a related one named in the text. Log them as WCAG failures.

  • A generic message such as "Invalid date" when the expected format is known doesn't provide the known suggestion.

Not required by the normative text

Common claims that this criterion does not support. Don't log these as WCAG failures.

  • Suggestions when the right answer can't be known or revealed, such as a wrong password.

Definitions used (1)

Glossary definitions are normative. Their notes are informative.

input error

information provided by the user that is not accepted

Informative notes (1)

This includes:

  1. Information that is required by the web page but omitted by the user
  2. Information that is provided by the user but that falls outside the required data format or values

Tier 2 ยท The gap

Usability & user impact

Where content can meet this criterion and still make things harder for people with disabilities. These are not failures of SC 3.3.3, so raise them as usability defects. Known failures, including failures of related criteria, are listed in Tier 1.

Correct suggestions can still be hard to act on, for example when they appear only in a summary at the top of a long form.

Tier 3 ยท The golden path

Recommended best practice

The pattern that meets the floor, closes the gap, and avoids audit disputes. A recommendation, not a requirement.

Say what's wrong and how to fix it, for example "Enter the date as DD/MM/YYYY".

W3C's Understanding document and techniques for SC 3.3.3 โ†— are informative: sufficient techniques show ways to pass, and documented failures show common ways to fail, but neither changes what the criterion requires.

How SC 3.3.3 maps to the WCAG 3 draft

From this site's reviewed map to the WCAG 3 editor's draft. It's an interpretation: W3C has not published a mapping.

Successor provisions

From WCAG 2.2, section 5.1: โ€œThe main content of WCAG 2.2 is normative and defines requirements that impact conformance claims. Introductory material, appendices, sections marked as "non-normative", diagrams, examples, and notes are informative (non-normative). Non-normative material provides advisory information to help interpret the guidelines but does not create requirements that impact a conformance claim.โ€