Bloggers are allowed to add categories, links, and postings to branches of the group blog. They can then edit those objects in their private area, and the changes show up in the group blog.
Bloggers are not allowed to rearrange the group blog. Meaning that they cannot rearrange the tree. Although they could delete and recreate their own objects elsewhere in the tree.
Bloggers are allowed to add edit and delete private categories in their private blog. They can rearrange their private blog. They can rename objects in their private blog.
Bloggors are allowed to delete the links and postings they created. They can only delete a category they created if that category is empty, both in the group blog, and in the private blog.