anchor.diff:            input(list="b" placeholder="select it or type it")
             datalist#b
               option option 1
  -            optgroup(label="label for option 2")
  -              option option 2a
  -              option option 2b
  -              option option 2c
  +            //- optgroup not a valid child of datalist
  +            option option 2
               option option 3
         figure(class=classnames.figure)
           fieldset
  
positive.code:       block documentation
          figure(class=classnames.figure): ul
            block documentation__list
              li: ins    content shown to be inserted into a document #[code(class=classnames.code) ins]
              li: del    content shown to be deleted from a document #[code(class=classnames.code) del]
              li: dfn    definining instance of a term  #[code(class=classnames.code) dfn]
              li: b      keyword or technical term #[code(class=classnames.code) b]
              li: var    variable  #[code(class=classnames.code) var]
              li: q      quoted material #[code(class=classnames.code) q]
              li: cite   reference to a work, some part of a work, or the creator of a work #[code(class=classnames.code) cite]
              li: sup    superscript #[code(class=classnames.code) sup]
              li: sub    subscript #[code(class=classnames.code) sub]
      section#data
        h3 Data
        block data
          figure(class=classnames.figure): ul
            block data__list
              li: abbr(title) abbreviation or acronym #[code(class=classnames.code) abbr[title]]
              li: time        a specific date or time #[code(class=classnames.code) time]
              li: data        generic machine-readable data #[code(class=classnames.code) data]
              li: code        a fragment of code #[code(class=classnames.code) code]
              li: kbd         user input #[code(class=classnames.code) kbd]
              li: kbd: kbd    a button or key on a physical device #[code(class=classnames.code) kbd &gt; kbd]
              li: samp        sample computer output #[code(class=classnames.code) samp]
  section#embedded-elements
    h2 Embedded Elements
    block embedded-elements
  
negative.code:       figure(class=classnames.figure)
          fieldset
            legend buttons
            input(type="button" value="button")
            input(type="reset")
            input(type="submit")
            button(type="button") button
            button(type="reset")  reset
            button(type="submit") submit
  