What's the real meaning of the member variables of class FPoly

I have readed polys.h,and i have seen the code below(it was code snippets in Polys.h,and it was the member variable of class FPoly):

FName RulesetVariation;
FName ItemName;
int32 iLink;
int32 iBrushPoly;
uint32 SmoothingMask;
float LightMapScale;

Please give me some explanations and some code samples,Thanks!!