upload

0 - nobody
[user_group] - members of user group + admins
1 - registered users

upload_images_only

0 - allowed users can upload all allowed files
1 - allowed users can upload only pictures, except admins

name space

global - all allowed users can upload

page - allowed users can upload when

1. page owner,
2. admin, or
3. allowed by ['upload'] page ACL

overwrite

file owner and admin can overwrite a existing file