/ wooden spear construction.

Construction		Source		Result
	0	pit	0	spiked pit
		is:DIGGABLE	#	fence post
		is:DIGGABLE	+	closed wooden gate
		is:DIGGABLE	+	closed wooden split rail gate
		is:DIGGABLE	+	closed wooden privacy gate
		is:DIGGABLE	LINE_OXOX	split rail fence
		is:DIGGABLE	LINE_OXOX	wooden privacy fence