OL's are a way for officers to keep an eye on the activity of members within the clan. They are only visible to us since we keep track of it on the player notes.
In a nutshell every week an officer will go give everyone an OL if that player comes online that week it will be removed.. after a certain numbers of OL that character might get kicked. But if you are active and/or let an officer or other clan member know when you will be going away for a prolonged period of time you will be okay.
Cheers
Bwoot