SVR II Question: "Main Work"?

S.V.R. II example workout shows main Work, 5s Pro.

What is the Main Work?

5/3/1.

Ok thanks

5/3/1 weights but with only 5:s, since the main work here is 5’s Pro?

I was thinking that was what was meant. What confused me was by writing it Main Work, 5s Pro. I didn’t see it written like that before. Usually just 5s Pro so, I thought I better ask. Thanks