program:	{ section | statement }

section:	"." WORD newline

newline:	[ space ] NEWLINE

space:		SPACE { SPACE }

statement:	( function | space [ instruction ] ) newline

function:	name [ space ] ":"

name:		WORD

instruction:	operator [ operand_list ]

operator:	WORD

operand_list:	operand { "," operand }

operand:	[ space ] ( value | address ) [ space ]

value:		symbol | register | immediate

symbol:		WORD

register:	"%" WORD

immediate:	"$" NUMBER

address:	"[" [ space ] value [ value ] [ "+" [ space ] offset [ space ] ] "]"