|%
++  down  (list barb)                                   ::  markdown structure
++  barb                                                ::  block elements
  $%  [%had p=@ud q=(list shin) r=(unit tape)]          ::  depth, contents, id
      [%hem p=manx]                                     ::  html tag
      [%hot ~]                                          ::  horizontal rule
      [%lie p=down]                                     ::  list element
      [%lit p=? q=down]                                 ::  list
      [%par p=(list shin)]                              ::  paragraph
      [%pre p=wall]                                     ::  preformatted text
      [%quo p=down]                                     ::  blockquote
  ==                                                    ::
++  shin                                                ::  span elements
  $%  [%cod p=tape]                                     ::  inline code
      [%cut ~]                                          ::  break
      [%emp p=?(%bent %bold %both) q=(list shin)]       ::  emphasis
      [%ike p=(list shin)]                              ::  strikethrough
      [%lin p=(list shin) q=tape r=(unit tape)]         ::  link
      [%tex p=tape]                                     ::  text
  ==                                                    ::
--