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Axe Core Guide

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Axe Core 4.9

IDs used in ARIA and labels must be unique

To avoid a second instance being missed by assistive technology, the value supplied to an id property used in ARIA or in form labels must be unique.

To put it another way, ID values used in ARIA and labels cannot be used more than once to distinguish one element from another in the same document.

Common validation problems like duplicate IDs can make labels, like ARIA elements, form fields, and table header cells, inaccessible.

Each element is distinguished from the others by a unique ID, which also prevents erroneous markup in which only the first instance is appropriately referenced by client-side scripting or assistive technology.

What this Accessibility Rule Checks

Assures the uniqueness of each ID used in ARIA attributes and the for property on a label.

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Related Accessibility Rules