Digraph.gv

// The Requirements
digraph {
rankdir=LR
size="200,50"
	"Mission-01" [label="Mission-01
User requirement"]
	"Mission-02" [label="Mission-02
Constraints"]
	"Mission-03" [label="Mission-03
Sounding Rocket"]
	"SCI-01" [label="SCI-01
Science requirement I"]
		"Mission-02" -> "SCI-01"
	"SCI-02" [label="SCI-02
Science requirement II"]
		"Mission-02" -> "SCI-02"
	"SCI-03" [label="SCI-03
Science requirement III"]
		"Mission-01" -> "SCI-03"
		"Mission-03" -> "SCI-03"
	"Tech-1" [label="Tech-1
Science bandpass"]
		"SCI-01" -> "Tech-1"
	"Tech-2" [label="Tech-2
IWA"]
		"SCI-01" -> "Tech-2"
	"Tech-3" [label="Tech-3
OWA"]
		"SCI-01" -> "Tech-3"
	"Tech-4" [label="Tech-4
Pointing Stability"]
		"SCI-02" -> "Tech-4"
		"SCI-03" -> "Tech-4"
	"Tech-5" [label="Tech-5
Telescope aperture"]
		"Mission-03" -> "Tech-5"
		"SCI-02" -> "Tech-5"
}