SQL & PL/SQL

Hi,

1)

Can someone explain me what is the BEQUEATH_CURRENT_USER view and how is it related with a PL/SQL function and AUTHID and CURRENT_USER?

I would think that the current schema, user, and enabled roles are inherited from the querying user's envoronment. But what if the current user calls a procedure from another user?

2)

For what is meant the INHERIT PRIVILEGE?

3)

What are invokers rights procedure?

4) A PL/SQL unit has by default AUTHID=DEFINER, but what means DEFINER?

Thanks and Regards.