.PS
cct_init
   ellipse "{\tt .m4}" "diagram"
   arrow right linewid*2/3
   { arrow <- left linewid*0.5 from Here+(0,boxht/3)
      line up linewid/3
      ellipse "{\tt .m4}" "macros" }
   move up boxht/6; right
   box wid boxht "{\bf m4}"
   arrow right linewid/2
   box "{\bf pic}" "interpreter"
   arrow right from Here-(0,boxht/6)
   { arrow <- left linewid*0.5 from Here+(0,boxht/3)
      line up linewid/3
      ellipse "{\tt .tex}" "files" }
   move up boxht/6; right
   box wid boxht "\LaTeX"
   arrow right linewid*2/3
   box wid boxht "{\tt .dvi}" "file"
.PE