@a_5mith I don't like docs either, but I think this might be useful (below), helping just one person will make me happy!
So... should anyone else be in the same situation I was:
- when everything is blank, it works with some defaults and mimics:
- admins: all boxes ticked
- registered-users: all boxes ticked
- guests: read-only access (find, access and read)
- when a permission is active (ticked), the other permissions come into effect (obey ticked or unticked state)