# Set the qualified name of a specific attribute.
	#
	# Parameters:
	#
	# * `index`: index of the attribute (zero-based).
	# * `qname`: attribute's qualified name, or the empty string for none.
	fun qname=(index: Int, qname: String) do
		assert index_in_bounds: index >= 0 and index < length
		data[index * 5 + 2] = qname
	end