Hi Pierre,

I do not know whether I understand you correctly, but I see that you have a y-value of -3mm, so the header-layer is moved towards the top, Setting this value to 0mm the pic aligns nicely with the cut marks ( I use LuaTeX, Version beta-0.74.0-2012122517 (rev 4541) ConTeXt  ver: 2013.02.20 14:35 MKIV  fmt: 2013.2.20  int: english/english)

Willi