Hi,
I don't know if I will explain my problem clearly but I will try. For my
students' tests, I use a master file. If I insert this piece of code, there
is a large white space that is created between the horizontal line of the
header and the first exercise.
Thanks for your help.
Fabrice

\startMPcode
  def suite (expr n, t) =
  begingroup
   numeric u;
   u := 5mm;
   pickup pencircle scaled 5pt;
   for i=0 upto n:
     for j=0 upto n:
         drawdot (i*u,j*u) shifted(t*u,0) withcolor \MPcolor{darkred};
     endfor
   endfor
  endgroup
  enddef;

  def Suite (expr n, t) =
  begingroup
  numeric u;
  u := 5mm;
  pickup pencircle scaled 5pt;
  for i=0 upto n:
     drawdot(i*u,0) shifted(t*u,0) withcolor \MPcolor{blue};
  endfor
  endgroup
  enddef;

  def cross (expr n, t) =
  begingroup
  numeric u;
  u := 5mm;
  pickup pencircle scaled 5pt;
  for i=-n upto n:
     drawdot(0,i*u) shifted(t*u,0) withcolor \MPcolor{blue};
  endfor
  endgroup
  enddef;
\stopMPcode
__________________________________________________________ %horizontal line
   % big unwanted white space
   \starttext
   % \startex First exercise
\startlinecorrection[blank]
        \startmidaligned
          \startcombination[1*2]
            {\startMPcode
              Suite(2,0);
              cross(1,1);
              Suite(4,4);
              cross(2,6);
              Suite(6,10);
              cross(3,13);
              \stopMPcode
            }{\tfx \bf Suite 1}
           {\startMPcode
              suite(0,0);
              suite(1,2);
              suite(2,5);
              \stopMPcode
            }{\tfx \bf Suite 2}
        \stopcombination
       \stopmidaligned
     \stoplinecorrection
  %\stopex
\stoptext