SIA-R45Headers attribute specified on a cell refers to cells in the same table element

Accessibility requirements

This rule tests conformance of the following accessibility requirements:

Description

This rule checks that the headers attribute on a cell refer to other cells in the same <table> element.

Applicability

This rule applies to every headers attribute specified on a cell within a table element, where the table element is visible and included in the accessibility tree.

Expectations

  1. Each target attribute is a set of space separated IDs, each of which is the ID of an element, that is a cell of the same table.

headers attribute referencing elements that are non-existent or not in the table are ignored when assigning header cells (step 3, first case, point 2).

  1. Each target attribute is a set of space separated IDs, none of which is the ID of the element on which the test target is specified.

headers attribute referencing to the cell itself are ignored when assigning header cells (step 3, first case, point 2).

Assumptions

  • This rule assumes that the headers attribute is only used to identify table headers. If other information is included in the headers attribute, the rule may fail on issues that are not accessibility concerns. For example, if headers is used to include information for scripts, this rule may not be accurate.
  • This rule assumes that the headers attribute is required to express the relationship between data and header cells in the table. If the browser computes an adequate fallback header, this rule may produce incorrect results.

Accessibility support

This rule has no known accessibility support concerns.

Examples

Acknowledgments

This document includes material copied from or derived from https://act-rules.github.io/rules/a25f45/. Copyright © 2021 W3C® (MIT, ERCIM, Keio, Beihang).