Glossary · Accessibility term
Set of web pages
A set of web pages is a collection that shares a common purpose and is created by the same author, group or organisation. Both halves have to hold, which draws the boundary in places people do not expect. The standard's own examples do the drawing. A checkout that strips the site navigation is a different set from the product pages it came from. A blog on a subdomain with its own navigation, written by a different group of people, is a different set again. And a translation is always separate from the original. Five success criteria are judged across a set rather than page by page, which is why consistency gets checked by opening several pages side by side instead of reading one of them carefully.
In practice
Judge these rules by opening several pages side by side, not one page carefully. Repeated navigation in the same relative order, the same control called the same thing, help offered in the same place in the running order. All of that gives way the moment the user asks for a change, because a reordering somebody chose is not a reordering you imposed.
Relative order is not the same as the same position, and the difference is a defence worth knowing. Items can be inserted or removed without breaking it, so a sidebar that moves to the top on a narrow layout still passes as long as the order holds. Consistent Help works the same way, and it never asks you to add help in the first place. It only asks that where one of four named kinds of help is repeated across pages, it turns up in a consistent place in the order. Contact details for a person. A way to reach one. A self-help option. A fully automated contact mechanism. An arbitrary hint sitting in your interface is not on that list.
It is the reason consistency rules cannot be checked on a single page, and the reason a page can pass alone and fail as part of a set. The failure is still recorded against that page, because the unit of conformance is always one page.
Why it matters
Renaming the same button from Search to Find between sections is invisible on either page and disorienting to anyone moving between them. Knowing where the set boundary falls cuts the other way too, because a checkout that drops the site navigation is answering to its own set and is not failing consistent navigation for doing it.
Passing alone, failing together
A shop where the basket is called Basket on one page, Cart on another and Bag in the header fails 3.2.4, even though each page reads perfectly well by itself. Any two of those names disagreeing would already be a failure, because every instance across the set has to agree.
Where this shows up on the site
Related terms
Knowing the word is the easy part.
Find out where your own site stands. The free scan checks 10 pages in a real browser against all 90 supported automated rules, separates 27 best-practice checks from its WCAG findings, and names the rule behind every result.