Hi,
In order answer that you have to make a MWE that we can run without the need to edit a file.
Hans
Sorry for having assumed that sharing the code was sufficient as MWE. Here is the trimmed version that still throws the error \startMPpage StartPage ; numeric row, col, unit; pair middle; row := 1; col := 1; unit := 2 * cm ; picture p, q ; p := nullpicture; q := nullpicture; string l[]; l[0] := "2" ; l[1] := " 4"; for i= 0 upto row : middle := (i * unit, 5cm); p := thelabel( l[i], middle); draw p; %q := p reflectedabout (0.5[urcorner p, ulcorner p], 0.5[lrcorner p, llcorner p]); %draw q endfor StopPage ; \stopMPpage \stoptext The file is also attached. As I told earlier, an error is thrown if I uncomment the line that assigns q and then draws it. Thanks for your help, ajith