; define high-level colon def list.
macro head name*, label, help {
	local nl, hl, nfa, hfa, lfa
nl:	align 4
	db nlen, name
	nlen = $-nl-1
hl: align 4
	db hlen, help
	hlen = $-hl-1
	align 4
nfa:	dd nl
hfa:	dd hl
lfa:	dd link
	link = nfa
}