anchor.diff:        dst=$out/share/doc/nixos
         mkdir -p $dst
         xmllint --xinclude manual.xml | dblatex -o $dst/manual.pdf - \
  +        -P target.database.document="${olinkDB}/olinkdb.xml" \
           -P doc.collab.show=0 \
           -P latex.output.revhistory=0
   
  
positive.code:     buildCommand = ''
        ${copySources}
  
        # Check the validity of the manual sources.
        xmllint --noout --nonet --xinclude --noxincludenode \
          --relaxng ${docbook5}/xml/rng/docbook/docbook.rng \
          ./man-pages.xml
  
negative.code:         --param man.output.base.dir "'$out/share/man/'" \
          --param man.endnotes.are.numbered 0 \
          --param man.break.after.slash 1 \
          --stringparam target.database.document "${olinkDB}/olinkdb.xml" \
          ${docbook5_xsl}/xml/xsl/docbook/manpages/docbook.xsl \
          ./man-pages.xml
      '';
  