I think a lot of things are clear now. I was not aware you were discussing "incremental" and "incremental-cumulative". I think "incremental" is what Sybex calls "incremental-diffrential".

Some points are clear now. I think, I also understood the importance of mapping (last paragraph).



But my last question is still unanswered - "As you said, even if it were 5 levels, lets say Level 4 blocks were changed yesterday and today I need to backup these "changed-Level 4 Blocks"; so what would my Level be then today?"

I would appreciate an answer for this last question. Anyway, I will get-on to do some serious reading again on this topic :-)

Many many thanks for your time and patience.