s6-l-i-m -R argument parser:

class	|	0	1	2	3	4	5
st\ev	|	\0	letter	=	0-9	,	other


START	|		g
0	|	END	ARG	X	X	START	X

ARG	|			=	m
1	|	X	X	WAIT	SCAN	X	X

SCAN	|	s				s
2	|	END	X	X	SCAN	START	X

WAIT	|
3	|	END	X	X	X	START	X

END = 4, X = 5

3 bits state
4 bits action

0x10	g	print letter
0x20	=	set max
0x40	m	mark
0x80	s	scan from mark