#m 6801	what machine this is for (first line only)
#foo	comment
x;y	two successive bytes
x y	two successive bytes
07	octal
0x7	hex
'c	character constant
'\n	ditto
foo:	label
x=100	definition (numbers only)
.=100	setting location counter (numbers only)
.=.+5	bumping location counter (numbers only)
.text	what it says
.data	ditto
.bss	ditto
=thing	two-byte constant
/thing	lower byte of 16-bit thing
\thing	upper byte of 16-bit thing
%thing	lower byte of 16-bit thing as an offset relative to PC
%%thing	upper byte of 16-bit thing as an offset relative to PC
