[NTG-context] Centering labels on A4 page

H..All..o... I am trying centering (horizontaly and verticaly too) labels on the A4 paper, but without success. Is there any possibility make it? Here is example code (see [NTG-context] XY arranging ignores dx/dy Angus Lees): \definepapersize[label][width=30mm,height=20mm] \setuppapersize[label][A4] \setuppaper[dx=1mm,dy=1mm,nx=5,ny=10] \setuparranging[XY] \showframe[edge] \starttext \dorecurse{50}{\page} \stoptext Labels are placed on left and top. I want to placed it to vertical and horizontal center (I want print doublesided cards) It certainly will be some pablum isnt it? :-) Thanx Jaroslav