--- a/acl.rst	Wed Jun 01 11:16:29 2016 +0300
+++ b/acl.rst	Wed Jun 01 11:23:03 2016 +0300
@@ -22,6 +22,10 @@
 
   $ sudo setfacl -x u:test ~/tmp/dir
 
+.. NOTE:: ``setfacl`` with ``-x`` key can't remove specific permission, you
+          should remove corresponding user or group and set new or explicitly
+          specify desired permission for user or group with ``-m`` option.
+
 Remove all ACL permissions::
 
   $ sudo setfacl -b ~/tmp/dir