Drop the write-only direction fields and the unused pattern names

main.go

@@ -34,10 +34,7 @@ func (e endpoint) macString() string {
 }
 
 type direction struct {
-	label   string
 	short   string
-	tx      endpoint
-	rx      endpoint
 	specs   []*frameSpec
 	txStats []*txStats
 	rxStats []*rxStats
@@ -450,10 +447,7 @@ func (d *direction) primeCounters() {
 
 func buildDirection(label string, tx, rx endpoint, sizes []int, cfg config) (*direction, error) {
 	d := &direction{
-		label:   label,
 		short:   tx.tag + "→" + rx.tag,
-		tx:      tx,
-		rx:      rx,
 		streams: newLossWindows(cfg.streams),
 		cable:   newCableStats(),
 	}