%externalpredicatespec FS lookup(%string(31) what, %integername value)

%begin
   %integername control
   %integer x
      %if FS lookup("LANCE_CONTROL", x) %start
         control == integer(x)
      %else
         printstring("No LANCE control word");  newline
         %stop
      %finish
      prompt("Control: ")
      read(control)
%end %of %program