What is the meaning of the columns in the statistics window?


I did not found anything about this tool you can access through Window->Statistics in the documentation. The meaning of some of the columns is clear, so with Object, Actors, Type, Count, Tris (Triangle Count), Sum Triangle Count etc.

Unclear are:

-Inst Sections
-Inst VC
-Avg LM, Avg OL, Cost, LM

What is the meaning of these columns?

Thank you,