To control access to a directory and all of the files in it, AFS associates an access control list (ACL) with it, rather than the mode bits that the UNIX file system (UFS) associates with individual files or directories. AFS ACLs provide more refined access control because there are seven access permissions rather than UFS's three, and there is room for approximately 20 user or group entries on an ACL, rather than just the three UFS entries (owner, group, and other).