On 2013–10–09 hwitloc@gmail.com wrote:

> I want a 3 mm border/edge and the rest of the space available for text space.

\definepapersize
  [business-card]
  [width=91mm,
   height=55mm]

\setuppapersize
  [business-card]

\setuplayout
  [backspace=3mm,
   topspace=3mm,
   margin=0mm,
   header=0mm,
   footer=0mm,
   width=middle,
   height=middle]

\starttext
  \showframe
  \midaligned{Hello World!}
  \showlayout
\stoptext

Marco