What Does '3 Back' Mean?

I have seen people here referring to something like 5 forward, 3 back, or something along those lines. What is this in reference to?

your TM

TM 350 0
TM 360 1
deload
TM 370 2
TM 380 3
deload
TM 390 4
TM 400 5
deload
TM 380 (or 370) back 3
TM 390 1
etc…

[quote]corndiggity wrote:
your TM

TM 350 0
TM 360 1
deload
TM 370 2
TM 380 3
deload
TM 390 4
TM 400 5
deload
TM 380 (or 370) back 3
TM 390 1
etc…
[/quote]
Thanks!