Change to Pandoc 2.8 beamer template to create PDF/A-2a

tagged-pres.diff

 *** default.beamer	2020-02-13 11:50:17.541486784 +0100
--- tagged-pres.beamer	2020-02-13 11:32:29.142235033 +0100
***************
*** 10,15 ****
--- 10,20 ----
  $endif$
  $endif$
  %
+ \begin{filecontents*}{\jobname.xmpdata}
+   \Title{$title$}
+   \Author{$author$}
+   \Language{$lang$}
+ \end{filecontents*}
  \documentclass[
  $if(fontsize)$
    $fontsize$,
***************
*** 33,38 ****
--- 38,45 ----
    $classoption$$sep$,
  $endfor$
  ]{$documentclass$}
+ \usepackage{luatex85}
+ \usepackage[a-2a]{pdfx}
  $if(beamer)$
  $if(background-image)$
  \usebackgroundtemplate{%
***************
*** 399,405 ****
--- 406,429 ----
  $endif$
  $endif$
  
+ \usepackage{etoolbox}
+ \BeforeBeginEnvironment{frame}{\tagstructbegin{tag=Sect}%
+    \tagstructbegin{tag=H}\tagmcbegin{tag=H}}
+ \AtBeginEnvironment{frame}{\tagmcend\tagstructend}
+ \AfterEndEnvironment{frame}{\tagstructend}
+ 
+ 
+ 
+ \usepackage{tagpdf}
+ \tagpdfsetup{
+  activate-all,
+  uncompress,
+  tabsorder=structure,
+  interwordspace=true
+  }
+ 
  \begin{document}
+ \tagstructbegin{tag=Document}
  $if(has-frontmatter)$
  \frontmatter
  $endif$
***************
*** 493,496 ****
--- 517,521 ----
  $include-after$
  
  $endfor$
+ \tagstructend
  \end{document}

The luatex85 package is necessary when compiling using Luatex > 0.85, or pdfx will complain about missing \pdfminorversion.