Link nonconforming pages to a conforming version
Read this one carefully. It is unlike every other technique on the site. G136 describes putting a link at the top of a page that does not conform, pointing at a version that does. W3C references it from no success criterion at all. It serves the conforming alternate version provision in WCAG's conformance section, which is normative but is not a rule you pass or fail on its own. So nothing here is a route through 1.4.3, 1.4.4, or anything else. What makes the mechanism work is strict. The alternate has to genuinely conform, carry the same information and functionality, and be reachable from the nonconforming page. That is why the link goes at the top, on every nonconforming page rather than on one of them.
How we find it in an audit
Where a site claims a conforming alternate version, our reviewers test the alternate rather than the claim. Is it reachable from every page it covers? Is the link first in reading and tab order, and does the alternate carry everything the original does? Then we audit the alternate itself against the level being claimed. An alternate that does not conform makes the whole arrangement worthless.
How affected users experience it
The whole idea only helps if the link is findable by the people it was built for. Bury it in a site map and a screen reader user meets the inaccessible version, works at it, and never learns the other one exists. Placing the link first means it is the first thing announced, which is also the moment it is most useful. Nobody wants to discover the accessible version after twenty minutes of struggling with the other one.
Passes vs. fails
Passes
The visualization page opens with 'View this data as an accessible table', first in tab order, leading to a version that fully conforms.
Fails
An interactive visualization fails several criteria, and the accessible table version exists but is linked only from the site map.
This guide is our interpretation of W3C technique G136: Providing a link at the beginning of a nonconforming web page that points to a conforming alternate version. W3C publishes its techniques as guidance rather than as the standard, and says so on every one of them. The success criterion is what conformance is measured against, and a technique is one documented way to meet it.