UVM class hierarchy - type of relationship

In reply to sharvil111:

Hi Sharvil,

I am not asking about functionality of these classes. These are readily available from UVM user manual. I am asking the class relationship between these classes.

To elaborate further, which classes have IS-A, HAS-A relation?
If yes, why is everything represented using an arrow with a white arrow head.
As per UML, there is a different representation for IS-A and HAS-A type of relation.

I hope my question is clear.