Need understanding of supersets....

CHeck out the example taken from GBC by TC.
I know these are supposed to be supersetted.
When does the resting part occur?? If u do leg curls and IMMEDIATELY seated row,where does the 45sec rest for leg curls occur? DURING the seated row? That’s what I assume…

A1) Lying Leg Curls Reps: 15-20 Sets: 3 Tempo: 201* Rest: 45 seconds Description: Pull toes in toward the body as you raise the weight and extend them away from the body as you lower the weight.

A2) Seated Cable Row to Neck Reps: 15-20 Sets: 3 Tempo: 211 Rest: 30 seconds