The command element
    with a type attribute whose
    value is "checkbox" represents a state or option
    that can be toggled.
empty (void element)
The command element is a void element. A command element must have a start tag but must not have an end tag.
any element that can contain metadata elements, any element that can contain phrasing elements
interface HTMLCommandElement : HTMLElement { attribute DOMString type; attribute DOMString label; attribute DOMString icon; attribute boolean disabled; attribute boolean checked; attribute DOMString radiogroup; };