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WCAG 2.2 · Guideline 3.2 · Understandable

Predictable

The interface has to behave the same way twice, and never change on its own.

People build a map of your site in their heads and then lean on it. Navigation stays where it was. The same icon keeps meaning the same thing. Tabbing into a field does not fire off a page load. This guideline protects that map. It protects it hardest for the readers who pay most to rebuild it, which is anybody seeing a small part of the screen at a time or hearing the page in one pass.

Five A/AA success criteria live here, out of six, and one of them is both newer and stricter than most teams expect. 3.2.6 Consistent Help arrived in WCAG 2.2 at Level A, which is the floor rather than the middle, so even a Level A audit covers it. What it asks for is order rather than position. A help link has to fall in the same place in the reading order across pages that share a purpose. A checkout counts as its own set of pages, rather than as part of the shop it came from. Nothing here can be cleared by a scanner either, because five of the six criteria have no automated test rule and the one that does is Level AAA. So the guideline is a heading, and the five rules underneath it are the work.

Rules
5
Level A
3
Level AA
2
Human testing only
5

All 5 Predictable rules

Level AAA in this guideline

One enhanced criterion sits under 3.2. They are outside the level almost every law names, so our audits treat them as reference rather than scope. Some are still worth adopting, and the Level AAA hub says which.

What goes wrong here

These are the failures we find repeatedly under 3.2, across sites of every size.

Who it affects

  • Screen reader users, who lose their place when the page changes without being asked and have to re-orient from the top.
  • People with cognitive disabilities, who depend on the interface behaving the same way the second time.
  • Screen magnifier users, who see a fraction of the screen and miss anything that changes outside it.
  • Anyone learning the product, which is everyone at first.

How to work through it

  1. 1Tab into every control and check that focus alone does not change the context. Content appearing or a field updating is not automatically a change of context, so judge what actually changed.
  2. 2Change a value in every select and checkbox. Either the page waits for a deliberate submit, or the behaviour was described before the control was used.
  3. 3Compare navigation across several pages of the same set, looking at relative order and at wording.
  4. 4Find every help mechanism that repeats across a set of pages and check it sits in the same relative order on each. The rule does not require help to exist, and a user-initiated layout change does not break it.
  5. 5Work out what your sets of pages actually are before you judge any of this. A set is defined by common purpose and authorship, so a checkout may well be its own set and a change of template alone does not make one.

How the levels build

Level A covers three. Focus alone does not change context, changing a setting does not change context without warning, and help repeated across a set of pages keeps the same relative order. That third one is new in WCAG 2.2 and lands at Level A, which surprises people. Level AA adds consistent navigation and consistent identification. Level AAA gives you a choice rather than a duty: either changes of context happen only when the reader asks for them, or a mechanism exists to turn such changes off.

Other Understandable guidelines

Part of the Understandable principle · browse by level: Level A · Level AA · or the full 55-rule library.

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