KOAL and KOAO settlements

Hello everyone,

When do settlements take place with transaction type KOAL, as opposed to KOAO?

We have a running PS set-up with hybrid projects (WBSEs and networks). Network activities are settled to WBSEs, which are in turn settled to either cost centers or profitability segments. These settlements normally take place with transaction type KOAO, which is what I prefer, but in some -exceptional- cases, they take place with KOAL or a combination of the two, instead. I have failed to detect a pattern here.

Thanks.