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)