[Scribus] pdf/x3

[Grzegorz Staniak]

Peter Linnell [mrdocs at gmail.com] pisze:
 
> > My printer wants my pdf in x1A format. He had problems with the png
> > graphic in my usual pdf file having a black background (which it
> > didn't). It looked fine when I previewed it in my Acrobat 5.0 viewer.
> 
> PDF/x1A is a bit different and not yet supported in Scribus. Note, the
>  PDF/X-3 is the latest and best at color mangement, if properly setup.
> 
> Only the latest RIPs can handle PDF/X-3 and imo, where the Europeans are more
> advanced (in general) than the North American printing industry.. See:
> http://fogra.org and http://eci.org for press profiles and info.

BTW, pardon a layman's question, but how does the "trim box" in PDF/X-3 work? 
I mean, I can set the width of the "trim box" in "PDF/x-3" tab when
exporting PDF, but when I view the PDF with the Acrobat Reader 5.0 it
looks just like any other PDF. I understand the trim box should allow me
to use bleeds (how? do I simply move objects in Scribus past the
margins?) and then specify in the PDF format that this-much should be
trimmed at the edges, but I cannot see the effect in AR 5.0.
 
Thanks for your time,

-- 
Grzegorz Staniak <gstaniak _at_ wp [dot] pl>