Candidate Set:

    Any element that has the aria-level attribute

    Except:

    table elements
    tr elements
    li elements
    elements with the aria role="grid"
    elements with the aria role="heading"
    elements with the aria role="listitem"
    elements with the aria role="row"
    elements with the aria role="tablist"
    elements with the aria role="treegrid"
    elements with the aria role="treeitem"