Conjunction Introduction

It looks like this:

The LPL rule of Conjunction Introduction

What does it mean?

It means that if you have all of the conjuncts,

P₁ through P_n,

of a conjunction,

P₁_^. . . _^P_n,

then you may claim that conjunction.

In the lines about the insertion point, you have the conjuncts, P1,..., Pn of the conjunction P₁_^. . . _^P_n. Therefore, you are entitled to enter P₁_^. . . _^P_n, at the insertion point.