shape-inside contributes to an element's wrapping context (cut from Exclusions in definition of wrapping context)

    </p>
        The <a href="#shapes">shape properties</a> can be used to change the shape of 
        <span>exclusion areas</span>.
    </p>
(cut from Exclusions section intro)

(which may be different 
            from the <span>exclusion box</span>
            because of the 'shape-outside' property).
(cut from step-2-B-layout-containing-block-applying-wrapping)