Hello Andrés!

On Wed, 11 Nov 2020 at 01:25, Andres Conrado Montoya Acosta <
elandi@chiquitico.org> wrote:

> may I ask someone, who understands knockout and overprint in the printing
>> press, to check test cases in the attached file from the test suite, if
>> overprint is working or not in Mark IV, please?
>>
>> Regards,
>> Jano
>>
>>
> Hi Jano, as far as I can check with my pdf editors, it seems overprinting
> is working. The black ink is printed above the blue, with no white reserve
> below it.
>

Sorry for the delay, I had to downsample the screenshots after the original
reply didn't get through (too big) and in the end remove them completely.

Thank you for checking. Looks like a bug in Acrobat (older version
11.0.23), not ConTeXt.
What editors do you use?

After your test I was digging deeper. When I disable black plate in *Preview:
Separations* it doesn't show an overprint, the room under the letters is
white (original problem). When I remove one overprint manually in
Illustrator, Acrobat shows the remaining overprints. I've found out later,
I could use *Profile: Color Warnings*, where all overprints are visible,
but I would rather see it in separated plates.

Hope this helps someone in the future, too.
Jano