AMT Datasouth PAL - Manual (Page 193)

187
stroke
% First build sub-path for loop which passes through box
36 51 moveto
47 51 lineto
47 41 lineto
43 41 lineto
43 47 lineto
54 47 lineto
% Next build sub-path for box which surrounds loop
39 55 moveto
51 55 lineto
51 37 lineto
39 37 lineto
closepath
% Specify line width & end cap style, then stroke sub-paths
2 setlinewidth
0 setlinecap
stroke