mode_setup;
 em#:=10pt#; cap#:=7pt#;
 thin#:=1/3pt#; thick#:=5/6pt#;
 o#:=1/4pt#;
define_pixels(em,cap);
define_blacker_pixels(thin,thick);
define_corrected_pixels(o);
 curve_sidebar=round 1/18em;
beginchar("O",0.8em#,cap#,0); "The letter O";
 penpos1(thick,10); penpos2(.1[thin,thick],90-10);
 penpos3(thick,180+10); penpos4(thin,270-10);
 x1l=w-x3l=curve_sidebar; x2=x4=.5w;
 y1=.49h; y2l=-o; y3=.51h; y4l=h+o;
 dz1=down; dz2=right; dz3=up; dz4=left;
 penstroke(1,2,3,4,cycle);
 penlabels(1,2,3,4); endchar;
def test_I(expr code,trial_stem,trial_width) =
 stem#:=trial_stem*pt#; define_blacker_pixels(stem);
 beginchar(code,trial_width*em#,cap#,0); "The letter I";
  penpos1(stem,15); penpos2(stem,12); penpos3(stem,10);
  x1=x2=x3=.5w; y1=h; y2=.55h; y3=0;
  taper2(.25,.1); dz2=down; penstroke(1,2,3);
  penlabels(1,2,3); endchar; enddef;

pausing:=1;
test_I("I",5/6,1/3);
end