% \setuppapersize[A4][A4,oversized] \showframe[text]

\setuplayout
  [location=middle,width=middle,height=middle,
   header=0cm,footer=0cm,
   backspace=5cm,topspace=3cm]

\definelayer
  [frame]
  [width=\paperwidth,height=\paperheight,repeat=yes]

\setupframed
  [width=\backspace,height=\topspace,
   background=color,backgroundcolor=gray:2,foregroundstyle=mono]

%% top
\setlayerframed
  [frame] [preset=lefttop] [align={right,top}]
  {preset=lefttop\par \type{align={right,top}}}
\setlayerframed
  [frame] [preset=middletop] [align={middle,top}]
  {preset=middletop\par \type{align={middle,top}}}
\setlayerframed
  [frame] [preset=righttop] [align={middle,left}]
  {preset=righttop\par \type{align={middle,left}}}

%% middle
\setlayerframed
  [frame] [preset=middleleft] [align={right,middle}]
  {preset=middleleft\par \type{align={right,middle}}}
\setlayerframed
  [frame] [preset=middle] [align={middle,middle}]
  {preset=middle\par \type{align={middle,middle}}}
\setlayerframed
  [frame] [preset=middleright] [align={left,middle}]
  {preset=middleright\par \type{align={left,middle}}}

%% bottom
\setlayerframed
  [frame] [preset=leftbottom] [align={right,low}]
  {preset=leftbottom\par \type{align={right,low}}}
\setlayerframed
  [frame] [preset=middlebottom] [align={middle,low}]
  {preset=middlebottom\par \type{align={middle,low}}}
\setlayerframed
  [frame] [preset=rightbottom] [align={left,low}]
  {preset=rightbottom\par \type{align={left,low}}}


\setupbackgrounds[page][background=frame]

\starttext
% \page[emtpy]
first page \page second page
\stoptext

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