Workout Tempo

[Nardies]

I've been trying out a training routine from the T-Muscle forum, but I'm getting confused when it comes to the tempo side of things. I get the idea of eccentric and concentric motion i.e 303 - Lift weight for 3 seconds, at the top of the motion immediately start back down again for 3 seconds.

However, some of them are listed like this:

Heels Elevated, Rock Bottom Front Squats

Sets: 6

Reps: 3,2,1,3,2,1

Tempo: 20X0

Rest: 3 minutes

Can anybody make head or tail of that?!