// Subsequent level-0 titles are allowed only for doctype book.
= Document Title
:doctype: book

= Part Title

== Section Level 1
>>>
Document
  { docMeta =
      Meta
        { docTitle = [ Inline mempty (Str "Document Title") ]
        , docTitleAttributes = Nothing
        , docAuthors = []
        , docRevision = Nothing
        , docAttributes =
            fromList [ ( "doctype" , "book" ) , ( "sectids" , "" ) ]
        }
  , docBlocks =
      [ Block
          Attr
          ( [] , fromList [ ( "id" , "_part_title" ) ] )
          Nothing
          (Section
             (Level 0)
             [ Inline mempty (Str "Part Title") ]
             [ Block
                 Attr
                 ( [] , fromList [ ( "id" , "_section_level_1" ) ] )
                 Nothing
                 (Section (Level 1) [ Inline mempty (Str "Section Level 1") ] [])
             ])
      ]
  }