You'll be getting the idea that the userclass code has had a fair amount done to it for 0.8.
You'll be getting the idea that the userclass code has had a fair amount done to it for 0.8. It's probably not obvious from the name, but there are two ways in which permissions can 'accumulate' when using hierarchical user classes. Its important to understand the difference.
The first way we shall call 'organisational', because it mimics the typical structure of an organisation. You have the all-powerful being (CEO, Managing Director, God, or whoever) at the top, and beneath him or her a layer of managers, who have lesser managers beneath them.... This is achieved by giving the user class at the top of the tree (often Main Admins) a parent of 'No One'. Permissions then accumulate as you get higher in the tree, culminating in this 'all-powerful' class that has all the permissions of everyone below them in the tree.
The second way we shall call something else (suggestions welcome). Here the 'lowest' class is the ordinary site member, and permissions accumulate as you go down the tree. A typical use is to have different grades of membership, or memberships covering different specialities.
Another little feature is the idea of a 'group' userclass - quite simply a class which 'contains' a number of other user classes. For example, if you have a userclass to represent each country, you may wish to have a group for Europe, a group for Asia...
For those who like to see what happens under the hood, log in as main admin (on a 0.8 site, naturally), go to the user class admin pages, and manually specify the page yoursite/e107_admin/userclass2.php?debug. This will show you the tree, including the class numbers used, class numbers below each class in the tree, accumulated permissions and so on. It also lists the first 10 users with their 'raw' permissions, and the class permissions they acquire due to the hierarchy.