TParent = object
    A : integer;
end;
TChild=object(TParent)
    B : integer;
end;
var
    Parent : TParent;
    Child : TChild;
  begin
     Child.A := 10;
     Child.B := 20;

     Parent := TParent(Child );//  is this always safe ? Will it copy

ONLY the 'A' field to 'parent'? Will it overwrite some memory space beyond the legitimate boundary of 'parent'?

end.

Thanks a lot in advance.