What is the "Section II-Security Data" section for on the ERB( Enlisted Record Brief)?

I am wanting to know that whole block is for and all of the fields in there mean. Like "PSI Status", "Fld Det PS Stat", "PSI Invest INIT", and "PSI Invest Compl". What are some answers that would go into those fields and what do they mean? Basically, I know what is in my ERB, but I am wanting to know if what it says is if I have a secret clearance or what.