>> Extended partitions are just like the complete disk, i.e. they have a MBR
>> of their own and thus can have again 4 partitions.  And yes, AFAIK that's
>> the way Linux _does_ their partitioning...
>
>No, they're even sicker.
>
>they create a type linux-root partition for 'a', and an extended partition
>for the rest of the disk.
>
>They create, inside that, a type linux-swap partition for 'b', and an extended
>partition for the rest of the disk.
 [...]

I've never seen a Linux system set up that way.  Are you sure?

p.