That,  Pablo, produces:

backend > profiles > setting format 'PDF/X-1a:2001' to 'PDF/X-1a:2001'

backend > profiles > forcing pdf version 1.3, compression level 3, object compression disabled

backend > profiles > permitted colorspaces: rgb 'yes', cmyk 'yes'

colors > defining > supported models: gray 'true', rgb 'true', cmyk 'true', spot 'true'

transparencies > support > transparency is supported

Again, I ask: is this acceptable for pdf/x-1a? In other words, if rgb is permitted and transparency is supported, is this acceptable?

Julian

On 5/18/25 10:46, jbf wrote:

[...] 
I guess my question can be reduced to something very simple: is the
result above acceptable for sending this pdf/x to a printer, given that
we are printing only in BW/grayscale and that IngramSpark insist on pdf/
x-1a?

In that case, how about the following?

\setupbackend
   [format=PDF/X-1a:2001,
    intent=sGrey-v4.icc,
    profile=sGrey-v4.icc]

Not sure whether this makes complete sense, but both you color profile
and your output intent are grayscale.

Pablo
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