So NOT ACL, from @Tom van der Lee reference
+ (plus) suffix indicates an access control list that can control additional permissions.
. (dot) suffix indicates an SELinux context is present. Details may be listed with the command ls -Z.
@ suffix indicates extended file attributes are present.
An example on my machine:
$ ls -l 35mm DNS-cache 
-rw-r--r--. 1 graeme graeme     60 Feb 27  2010 35mm
-rw-r--r--  1 graeme everyone 5193 Jun  1 14:45 DNS-cache
$ 
$ getfacl -s 35mm DNS-cache 
$ ls -Z  35mm DNS-cache 
unconfined_u:object_r:user_home_t:s0 35mm
                                   ? DNS-cache
So the getfacl -s produced no output, because there was no ACL. There was however a security context (seen with ls -Z)