anchor.diff:              sup
                 +footnote('summary')
               | The #[code summary] element may contain either Phrasing Content, or exactly 1 Heading Element (#[code h1]&ndash;#[code h6])
  +          li
  +            sup
  +              +footnote('main-caveat')
  +            | There is one exception: the #[code main] element may be a descendant of #[code section],
  +            |  however I prefer to restrict this use anyway. In fact, I adhere to the belief that
  +            |  there should be exactly 1 #[code main] element per document, and that it should be
  +            |  a direct child of #[code body].
       script(src="https://code.jquery.com/jquery-2.2.4.min.js" integrity="sha256-BbhdlvQf/xTY9gja0Dq3HiwQF8LaCRTXxZKRutelT44=" crossorigin="anonymous")
       script(src="https://cdn.mathjax.org/mathjax/latest/MathJax.js?config=TeX-AMS-MML_HTMLorMML,https://chharvey.github.io/chhlib/mathjax-localconfig.js")
  
positive.code:             | Each #[dfn#sectioning-content Sectioning Content] adds a section to the #[span.c-Acro DO].
            li
              sup
                +footnote('hr-nothing-content-model')
                +footnote('col-nothing-content-model')
                +footnote('br-nothing-content-model')
  
negative.code:               The #[code footer] element should contain secondary information, data about
                #[em the content in the section], such as copyright information, contact information,
                related links or references, and footnotes.
            li.
              #[code h1]&ndash;#[code h6]
              #[+tag('Phrasing Content Model','hn-phrasing-content-model')]
              #[+tag('Heading Content','hn-heading-content')]
            li #[code address] #[sup: +reference('address')]
          footer.c-Document__Draft
            p There are certain rules regarding the allowed nesting of certain sectioning elements:
            ul
              li.
                The #[code main] element #[em may not] be a descendant of any #[b Sectioning Content]
                elements.#[sup: +reference('main-caveat')]
                The #[code main] element also #[em may not] be a descendant of any
                #[code header] or #[code footer] element.
              li.
                Any #[code header] or #[code footer] element (in addition to prohibiting any
                #[code main] element descendants) #[em may not] contain any other
                #[code header] or #[code footer] elements, #[em unless] those said elements are
                descendants of a Sectioning Content element, which, in turn, is a descendant of
                the original #[code header] or #[code footer].
              li.
                The #[code address] element #[em may not] contain #[b Sectioning Content],
                #[b Heading Content], #[code header]s, or #[code footer]s.
        section#grouping-content
          h2 Grouping Content
          p May be used where Flow Content is expected.
  