my $string = "q\n";         # save graphic state
         $string   .= "4 w\n";       # make line width 4 pixels
         $string   .= "10 600 m\n";  # move to x=10 y=600, starts a new subpath
         $string   .= "40 600 l\n";  # a line to x=40 y=600 ( a horizontal line)
         $string   .= "10 580 m\n";   
         $string   .= "40 580 l\n";   
         $string   .= "10 510 m\n";   
         $string   .= "40 510 l\n";
         $string   .= "s\n";         # close the path and stroke
         $string   .= "Q\n";         # restore graphic state
         prAdd($string);             # the string is added to the content stream