Description of bug or feature request

We currently support aria-selected on gridcells, but aria-checked provides certain additional features that seem worthwhile to be able to use in a grid:

• mixed-state selection
• multiple selection, where checked/unchecked state is more consistently exposed and more user-friendly than selected/unselected state

A specific use case where this came up was in a grid with selectable rows, where the first cell in each row contained a checkbox, but we wished to expose the checked/unchecked state directly on the focused gridcell element, and potentially on the rowheader cell as well (as it is the most common column users navigate through).

The proposal would be to:

• Add aria-checked as a supported state on gridcells and rows
• Add the same checked vs. selected wording that currently exists on treeitems/options to gridcells and rows

Will this require a change to CORE-AAM?

It's possible it might require a change, since all other roles that support aria-checked do note that fact and link to the aria-checked mapping from the role mapping section. I'd personally lean against explicitly adding it though, since we don't do so for aria-selected or other optional states.

Will this require a change to the ARIA authoring guide?

No