digraph asde91 {
     ranksep=.75; size = "7.5,7.5";
     {
     node [shape=plaintext, fontsize=16];
     /*
     the time-line graph
     */
     past -> 1978 -> 1980 -> 1982 -> 1983 -> 1985 -> 1986 ->
     1987 -> 1988 -> 1989 -> 1990 -> "future 将来";
     /*
     ancestor programs
     */
     "Bourne sh"; "make"; "SCCS"; "yacc"; "cron"; "Reiser cpp";
     "Cshell"; "emacs"; "build"; "vi"; "<curses>"; "RCS"; "C * ";
     }
     { rank = same;
     "Software IS"; "Configuration Mgt"; "Architecture & Libraries";
     "Process";
     };
     node [shape=box];
     { rank = same; "past"; "SCCS"; "make"; "Bourne sh"; "yacc"; "cron"; }
     { rank = same; 1978; "Reiser cpp"; "Cshell"; }
     { rank = same; 1980; "build"; "emacs"; "vi"; }
     { rank = same; 1982; "RCS"; "<curses>"; "IMX"; "SYNED"; }
     { rank = same; 1983; "ksh"; "IFS"; "TTU"; }
     { rank = same; 1985; "nmake"; "Peggy"; }
     { rank = same; 1986; "C * "; "ncpp"; "ksh-i"; "<curses-i>"; "PG2"; }
     { rank = same; 1987; "Ansi cpp"; "nmake 2.0"; "3D File System"; "fdelta";
     "DAG"; "CSAS";}
     { rank = same; 1988; "CIA"; "SBCS"; "ksh-88"; "PEGASUS/PML"; "PAX";
     "backtalk"; }
     { rank = same; 1989; "CIA++"; "APP"; "SHIP"; "DataShare"; "ryacc";
     "Mosaic"; }
     { rank = same; 1990; "libft"; "CoShell"; "DIA"; "IFS-i"; "kyacc"; "sfio";
     "yeast"; "ML-X"; "DOT"; }
     { rank = same; "future"; "Adv. Software Technology"; }
     "PEGASUS/PML" -> "ML-X";
     "SCCS" -> "nmake";
     "SCCS" -> "3D File System";
     "SCCS" -> "RCS";
     "make" -> "nmake";
     "make" -> "build";
     }