Logistics mainly. People also know them as “Leader’s Books” or “Green Books”
Just an “official” journal for people to help track mission status.
Mine was one of the big aluminum closing clipboards. Had all my loadout lists, sortie schedules, point-of-contacts, etc, in it. Friend of mine at the paint shop did me up a decal that covered the face of it. Had my name, rank, and the happy phrase “Is taking this really worth your life?” on the front cover of it.