The resulting PDF can be verified using the Apache PDFBox preflight app.
```
$ java -jar preflight-app-2.0.8.jar test.pdf
The file test.pdf is a valid PDF/A-1b file
```
Instructions on how to install the ICC profiles on ConTeXt standalone can be found in the wiki: <http://wiki.contextgarden.net/PDFX#ICC_profiles>.
If the ICC profiles are not available the log will contain messages like these
```
backend > profiles > profile specification 'sRGB.icc' loaded from '/usr/local/texlive/2017/texmf-dist/tex/context/colors/icc/context/colorprofiles.xml'
backend > profiles > error, couldn't locate profile 'srgb.icc'
backend > profiles > no default profile 'srgb.icc' for colorspace 'rgb'
backend > profiles > profile specification 'sRGB IEC61966-2.1' loaded from '/usr/local/texlive/2017/texmf-dist/tex/context/colors/icc/context/colorprofiles.xml'
backend > profiles > error, couldn't locate profile 'srgb.icc'
backend > profiles > invalid output intent 'sRGB IEC61966-2.1'
```
and the resulting PDF will not be valid PDF/A:
```
$ java -jar preflight-app-2.0.8.jar test.pdf
The file test.pdf is not a valid PDF/A-1b file, error(s) :
2.4.3 : Invalid Color space, The operator "g" can't be used without Color Profile on page 1
2.4.3 : Invalid Color space, The operator "G" can't be used without Color Profile on page 1
2.4.3 : Invalid Color space, /DeviceGray default for operator "TJ" can't be used without Color Profile on page 1
2.4.3 : Invalid Color space, /DeviceGray default for operator "TJ" can't be used without Color Profile on page 1
2.4.3 : Invalid Color space, The operator "g" can't be used without Color Profile on page 1
2.4.3 : Invalid Color space, The operator "G" can't be used without Color Profile on page 1
2.4.3 : Invalid Color space, /DeviceGray default for operator "TJ" can't be used without Color Profile on page 1
```
However, the PDF will still be generated and the "errors" shown in the log do not break anything.
