A *.vtm file defines the transition function of a turing machine which
can be run by the vtm program.  It may also set other command line
options on the first line.

Each transition function line should have 5 strings, separated by commas :
 
 in_state,  in_symbol, out_state, out_symbol, direction

where

 in_state   = the state of the machine before the transition
 out_state  = the state of the machine after the transition

 in_symbol  = the symbol read from the tape
 out_sybmol = the symbol written to the tape, replacing in_symbol

 direction  = L or R (left or right) movement of the tape reader position

Lines which have a # sign in the left column are ignored.

Lines which start with ##echo are printed, if the -Q (quiet) option isn't on.

If the file is executable and the first line is #!/usr/bin/local/vtm 
(or whatever the path to the vtm C executable wrapper is), 
then any of the command options on the first line may be used
to set the start state, the tape, and so on.

 -F         Finite tape mode.
 -I         Infinite tape mode (well, it grows anyway) (default).
 -S         Show the state at the end of each line (default).
 -T         Don't show the state at the end of each line.
 -V         Shows tape, blank character, and starting state before running.
 -W         Don't show anything before running.
 -Q         Ignore ##echo directives.
 -L         Enable ##echo directives.
 -0         Show zero lines of output per step; only show the final tape.
 -1         Show one line of output per step of the Turing machine (default).
 -2         Show two lines of output per step of the Turing machine.
 -tXXX...   Set the value of the initial tape.
 -bC        Set the value of the blank character.
 -sState    Set the value of the starting tape.

Look in ./machines/ for examples.