Understanding the HCA graph

[niceguymr]

What is the difference between the solid white lined box/enclosure and the dotted white line?

I understand that the ''X'' is where the culet is and that it should fall within one or both of those boxes. Can someone just explain that to me just a little better?

 

[belle]

the 'x' represents the diamond itself and the placement shows where it would potentially fall within each of the top grading labs' system. the solid line is ags 'ideal' and the dotted line is gia 'excellent'.

 

[Garry H (Cut Nut)]

Leonid and co are travelling for a few days and will put up some explanations on the hCA site when they get home.
thanks for the explanation Belle