PDF/UA-1 Default Article Namespace section H1 subsection H2 subsubsection H3 paragraph H4 subparagraph H5 LaTeX Book structure Namespace chapter H1 section H2 subsection H3 subsubsection H4 paragraph H5 subparagraph H6 part Title section-number Span figures Sect tables Sect float Aside Note theorem-like Sect text-unit Part verbatim P Code codeline Sub Span list L itemize L enumerate L quote BlockQuote quotation BlockQuote description L title Title text P footnotemark Lbl footnote FENote Note footnotelabel Lbl