% PDF/A-3u

\enabletrackers[backend.xmp]

\setupbackend
  [format=PDF/A-3u,
   intent=sRGB IEC61966-2.1, % use <info> entry here; otherwise problems with predefined default profile
   profile={sRGB.icc,default_gray.icc},
   level=0]

\setupinteraction[state=start]% needed for attachment
%\setupattachment[method=hidden]

\setupcolors[cmyk=no]
\definecolor[rgbblack][b=0.01]
\definecolor[transtest][r=1,g=1,t=.25]

\placebookmarks[chapter][all][force=yes]



\starttext

\starttextcolor[rgbblack]

\startchapter[title=aa,bookmark=bb,list=cc,marking=dd]

Test for PDF/A-3u

\stopchapter

\stoptextcolor

\hbox\bgroup
    \blackrule[width=1cm,height=1cm,color=red]
    \blackrule[width=1cm,height=1cm,color=green]
    \blackrule[width=1cm,height=1cm,color=blue]
    \blackrule[width=1cm,height=1cm,color=rgbblack]
    \blackrule[width=1cm,height=1cm,color=transtest]\hskip-.5cm
    \blackrule[width=1cm,height=1cm,color=transtest]
\egroup


% inclusion of any file type is allowed
\attachment[file=cow.pdf, type={application/pdf}]

\stoptext