Self means that if you are the creator of the content you will be the only one to be able to modify it. It is the same behavior thant your post in this forum. You are only able to modify your post.
I understand what "self" does when its used on the "Owner" option of the function limitation, what I don't know is what does the "Group" option do? This option doesn't exist on my 3.8.x installs but it does exist on my 4.0.0 install.