define(`shadellipse',`{ellipse $1 fill invis
define(`m4h',`1.0 pt__')dnl
ellipse invis fill 0.5 wid last ellipse .wid+linethick pt__ \
ht last ellipse .ht + linethick pt__ at last ellipse+(m4h,-m4h)}
ellipse fill 1 $1')
shadellipse "{\tt .m4}" "diagram" "source"
arrow right linewid*0.6
shadellipse "configuration"
arrow right linewid*0.6
{shadellipse(with .b at Here+(-linewid*0.5,boxht/3+linewid/3)) \
"{\tt .m4}" "library" "macros"}
arrow from last ellipse.b down linewid/3 then right linewid*0.5
move down boxht/6; right
shadebox(box wid boxht "{\bf m4}")
arrow right linewid/2
shadebox(box "{\bf pic}" "interpreter")
arrow right from Here-(0,boxht/6)
{shadellipse(with .b at Here+(-linewid*0.5,boxht/3+linewid/3)) \
"{\tt .tex}" "files"}
{arrow from last ellipse.b down linewid/3 then right linewid*0.5}
move up boxht/6; right
shadebox(box "\LaTeX" "PDFlatex" "etc.")
arrow right linewid*0.6
