Screen recording SHDB doubts

Hi friends,

While recording the screen transactions for a particular transaction code..I have come to see this "UPDATE MODE"  and "CATT MODE" options under the SHDB.

Update Mode - Synchronous, Asynchronous and Local.

Catt Mode - No Catt,

                  Catt without individual screen control,

                  Catt without individual screen control.

Can you please explain me what this use of the above two options which are available under the transaction code "SHDB".

Thank you friends,

with regards,

Kumar.