figs1.tex

\def\figfont{\footnotesize\sl}
\dh=\fbh
{\setbox0\hbox{$\downarrow$}
 \global\lh\ht0 \global\advance\lh by -\fontdimen22\textfont2 %MathSYx
 \setbox0\hbox{\quad0+11,11, \dots}
 \global\dw\wd0 \global\advance\dw by 10pt }

\def\doosje#1{\hbox
   {\vrule width\lw
    \vbox to \dh{\hsize\dh
        \hrule height\lw \
        \vfil \hbox to \hsize{\hfil#1\hfil} \vfil
        \hrule height\lw}%
    \vrule width\lw
   }}
\def\mr{\moveright.5\dh}
\def\hdoosje#1#2#3{\vtop
   {\vbox{\hbox to \dh{\hfil$\swarrow$ \raise5pt\hbox{#1} $\nwarrow$\hfil}
          \doosje{#2}\kern0pt}
    \hbox to \dh{\hfil
      \vtop{\kern0pt 
       \downvector{12pt}
       \kern3pt
       \setbox0\hbox to 0pt{\hss14\setbox2\hbox{5}\hskip-.2\wd0}
       \dp0=0pt \box0
       \kern3pt
       \downvector{12pt}}
      \kern5pt 
      \vtop{\kern0pt 
       \downvector{12pt}
       \kern3pt
       \setbox0\hbox to 0pt{#3\hss}
       \dp0=0pt \box0
       \kern3pt
       \downvector{12pt}}
      \hfil}
    \kern7pt
    \hbox to \dh{\hfil stop\hfil}}\ignorespaces
   }

\font\linefnt=line10
\newdimen\lfw \lfw=\fontdimen8\linefnt
\def\downvector#1{\hbox{\hbox to 0pt
    {\vrule width\lfw height0pt depth #1\hss}%
    \lower#1\hbox to 0pt{\linefnt\char'77\hss}}}

\def\tbox#1{\setbox0\hbox{\quad#1\quad}\dimen0=\wd0 \box0\relax}
\def\abox{\hbox to \hsize{\rightarrowfill}}

\def\tarrow#1{\raise.5\dh\vbox{\tbox{#1}\hsize\dimen0\relax
    \abox}\ignorespaces}
\def\threearrow{%
    \vbox{\hsize\dw
          \vbox{\tbox{10}\abox
                \kern2pt
                \tbox{0+11,11, \dots}\abox}
          \kern2pt
          \tbox{0+10}
          \abox
          \kern2pt
          \vtop{\kern0pt
                \hbox to \dw
                   {$\nwarrow$\hfil\lower 5pt\hbox{other}%
                    \hfil$\swarrow$}}
          }}

\def\figmouth{\hbox{\leftskip=0pt \parindent=0pt \offinterlineskip
    \figfont %\SansSerif \PointSize:8 \Style:roman
    \tarrow{start}%
    \hdoosje{10}N{5: insert \cs{par}}
    \tarrow{other}
    \hdoosje{other}M{5: insert space}
    \threearrow
    \hdoosje{10}S{5}
    }}

\endinput