create folder with a flag +1 user, and then try to put something in that dir with a flag +3 user, you will find that you are unable to upload even though permissions for that dir is 777.
also if +3 user makes a dir, the +1 users uploaded file will have the +3 user as owner
edit: weeee 200 posts made by me so far hehe
edit 2: noticed I put this thread in the wrong part of the forum, sorry about that..