generic with procedure

["Rick Santa-Cruz" <rick_santa_cruz75@msn.com>]

Hi,

I am starting to read a bit about generic programming and I am a bit 
confused from it, cause it seems to me a bit different to 
template-programming in C++.
Sadly I can't figure out the difference between the following:
1.) generic
        type Element is private;
    package MyContainers is
        type MyContainer is private;
        procedure Some_Proc(Item : Element);
    end MyContainer;
2.) generic
        type Element is private;
    package MyContainers is
        type MyContainer is private;
     generic
        with procedure Some_Proc(Item : Element);
    end MyContainer;

I only have seen the "with procedure/function..." in the following sense:
generic
    type T is private;
    with procedure Some_Proc(Item : Element);
And I thought the sense of this is to tell the compiler that T has to 
declare the procedure Some_Proc, so that I can write in the body of my 
package something like:
....
Item1, Item2: Element

...
Item1.Some_Proc(Item2);

I sadly don't understand when to use the 2. case?

Thanks in advance,
Rick