On this page:
Make sure the HTML does not contain markup errors that are known to cause conflicts with assistive technologies (such as incorrect nesting of elements, or duplicate
ids). [Web only]
ids are unique within a page.
idattributes use duplicate values within the same page;
This ensures that content and functionality is presented in a way that works reliably across all supported browsers and assistive technologies.
4.1.1 Parsing: In content implemented using markup languages, elements have complete start and end tags, elements are nested according to their specifications, elements do not contain duplicate attributes, and any IDs are unique, except where the specifications allow these features. (Level A)
See the W3C’s detailed explanation of this guideline with techniques and examples.
roleattributes are nested correctly
roleattribute, look at the
role’s definition in the W3C ARIA 1.1 specifications to check whether you’re nesting elements with that role correctly.
idattributes are unique on a Web page technique in the Web Content Accessible Guidelines